If you used real dark chocolate then it's probably blooming. Your second picture looks like a bloom, but then I re-read your post and saw that you used powder so all of the info below is a moot point. I don't know the makeup of the poweder, so i don't know the cocoa butter content which would make the below answer apply. So it may apply to some degree. I left my answer as is just as a FYI for learning. Just in case you do use real dark chocolate next time.
If temperature exceeds 75°F, some of the cocoa butter may appear on the surface, causing the chocolate to develop a whitish cast, known as "bloom."
Blooming of chocolate products is the most common problem you will encounter. There are two forms of "bloom": fat bloom and sugar bloom.
* Fat bloom is the visible accumulation of large cocoa butter crystals on the chocolate surface. It may feel silky, looks whitish grey and dull and is often accompanied by numerous minute cracks that dull the appearance of the chocolate. However, when touched with a warm hand or finger it goes away, due to melting of the cocoa butter. But it will come back due to the chocolate not being tempered at the correct temp in the first place. the only thing to do is to remelt it and temper it correctly.
* Sugar bloom is a crystallization of sugar that is often caused by high humidity and the formation of condensate ("sweating") when cold product is brought into a warm area. The moisture evaporates leaving the sugar crystal behind. When touched it feels like sugar and it does not disapear due to your warm touch. Once again it must be re-done to make it look good.
