Prolonged exposure to heat may eventually result in loss of flavor, but usually, cocoa butter bloom has little or no effect on a chocolate's quality. The worst it can do is make your chocolate chips look as though they've got leprosy. They are safe to use, and the discoloration usually disappears on melting and resolidification. But sometimes it doesn't.
thanks to:
http://www.gourmetspot.com/factschocolate.htm
http://www.hersheys.com/visit/smithsfalls/faq.html
http://www.chocolatevalley.com/glossary/dictionary.htm
http://www.masterstech-home.com/The_Kitchen/Articles/ChocolateNutritionFAQ.html
http://www.expresshotelierandcaterer.com/20010521/inside1-2.htm
http://www.aarhus.com/about_aarhus/indhold/why/downloads/booklets/confao_illexao_uk.pdf