British chocolate melts easily!
The customer assumes the risk when ordering chocolate biscuits.
When European Chocolate is exposed to Temperature changes as we have between States here in the US, the chocolate may "Bloom". "This is the light discoloration you sometimes see on chocolate, it happens when the cocoa butter separates from the cocoa solids. They are fine to eat, just not as pretty. It does not spoil the chocolate in any way other than aesthetically.