I've had something happn to me that was along the lines of what you're describing. I rehydrated some weed that had gotten a bit dry, and a few days later I noticed that sections were a bit whiter than usual. Thought it was mold, but smoked it anyway (in the name of science!). Seriously, got me just as high, and nothing bad happened. If there is actually mold on your weed, I'm sure the flame gets rid of most of the harmful bits.

However, if it starts to move and talk, then you got problems. :rasta: