[gorbelly]

That looks a lot like frost damage to me. Did you happen to get temps down to or close to freezing recently? Frost damage can happen at temps slightly above freezing, too, depending on some different variables, and lower leaves being affected could be consistent with lower temps near the ground, too.

EDIT: never mind. I just read where you said the leaves had been off the plant overnight and saw another post where you talk about growing indoors. It's best to see damage on the plant itself or immediately after it's been pruned off.