Do you even have moldy weed? Without seeing the weed myself, I'd actually lean toward your first guess of the volatile terpenes being released. It would be obvious as hell if your weed was moldy.
Well, I'll answer that since I'm the real thread starter. I know the look of mycelium. Some deeper indents in the buds had the white hairs bridging the gap. The contrary evidence is, no ammonia smell. And I can't figure out how it made spores so fast. And I've never seen white spores, though I know them to exist. That smoke was white.
I'll do an experiment on a future batch from the same plant and report back. I'll dry it in the fridge with gel packs in a jar. Being that cold, minimal terpenes should evaporate on their own.
Then when it's dry enough to prevent mold I'll put it back into the jar in the warm room temps, and shake it each day to see if it gets the cloud.
Speaking of the moldy pot, someone said to toss it out. Instead I did a 91% iso extraction on it in the freezer, and got surprisingly good quality shatter from it, for having used such a poor solvent. It only had minimal chlorophyl in it, and was completely clear.