With bloom it indicates that the cocoa butter crystals (aka fat crystals) didn't form properly but since you were careful about the temperatures it likely was as a result of too little or too much stirring. Bloom, as you probably know, doesn't prevent the chocolate from being edible... it affects appearance and occasionally mouth-feel. Even pro's have tempering misses and, just in case it happens, I recommend having a bit of very finely chopped nuts, pulverized praline, specialty sugar, or candied flowers or herbs on hand to sprinkle on top and disguise the bloom.
More about tempering:
Tempering is about heating and cooling in order to get the cocoa butter crystals (6 types, if I remember correctly) to form properly resulting in smooth shiny chocolate with no streaks. This occurs using precision in the temperatures (melting, cooling, holding) but also precision in stirring. Too much stirring and the proper crystals won't form (usually resulting in a sticky end-product with some bloom), too little and the cocoa butter will separate from the chocolate (resulting in a dry dull product with quite a bit of bloom). If you're using a heating pad, it's important to place a thermometer on it in order to monitor the temperature (heating pads with their own temperature dials are not accurate enough for chocolate so using a thermometer is important), placing the pot back on the hot water bath in order to keep the temperature within a couple degrees of ideal (ideal temperature can also vary by product... Valrhona, for instance, is more tolerant of temperature variations and can take more heat). When you believe you're at temper, dip a knife into the chocolate, and let it sit for about 30 seconds. Observe the chocolate and you'll see if it's ready if it sets properly and is shiny... or... if it shows evidence of bloom. I've also found it most helpful to remove a quantity of tempered chocolate to a surface (or warmed bowl) for dipping. That way my introduction of cooled centers doesn't impact the temperature of the tempered chocolate (and I can lengthen the dipping time).
Again, even pro's have misses, so just keep something tasty on hand to sprinkle on top if the chocolate is out of bloom (or drizzle on some melted white, milk, or dark chocolate afterward - or - dip the tops).
Hope some of that helps and, finally, my own personal philosophy is that if the chocolate doesn't quite look how I want it to look just 'eat the evidence!'
RuthSF
More about tempering:
Tempering is about heating and cooling in order to get the cocoa butter crystals (6 types, if I remember correctly) to form properly resulting in smooth shiny chocolate with no streaks. This occurs using precision in the temperatures (melting, cooling, holding) but also precision in stirring. Too much stirring and the proper crystals won't form (usually resulting in a sticky end-product with some bloom), too little and the cocoa butter will separate from the chocolate (resulting in a dry dull product with quite a bit of bloom). If you're using a heating pad, it's important to place a thermometer on it in order to monitor the temperature (heating pads with their own temperature dials are not accurate enough for chocolate so using a thermometer is important), placing the pot back on the hot water bath in order to keep the temperature within a couple degrees of ideal (ideal temperature can also vary by product... Valrhona, for instance, is more tolerant of temperature variations and can take more heat). When you believe you're at temper, dip a knife into the chocolate, and let it sit for about 30 seconds. Observe the chocolate and you'll see if it's ready if it sets properly and is shiny... or... if it shows evidence of bloom. I've also found it most helpful to remove a quantity of tempered chocolate to a surface (or warmed bowl) for dipping. That way my introduction of cooled centers doesn't impact the temperature of the tempered chocolate (and I can lengthen the dipping time).
Again, even pro's have misses, so just keep something tasty on hand to sprinkle on top if the chocolate is out of bloom (or drizzle on some melted white, milk, or dark chocolate afterward - or - dip the tops).
Hope some of that helps and, finally, my own personal philosophy is that if the chocolate doesn't quite look how I want it to look just 'eat the evidence!'
RuthSF