Yes, I've noticed this for a long time. I frequently will recrystalize my spice only to melt the entire thing down. The experience, for whatever, reason, at the exact same dosage, is much more powerful. Put 100mgs or so in a mason jar or cup and stick it in a bowl of pretty hot water...let the spice melt completely and stick the jar in the freezer until the spice is solid again.
Try it out. I've never head of anyone else testing this theory out. I'd really like someone else's verification that my experience can be duplicated in others.