What is this on my plant????

[nugatronica]

Any ideas what it could be yet?

[ThePinkJina]

I understand you don't see any mites or parasites, but it looks like a leaf miner or caterpillar attack.

[EvilCartman]

G_Man, is this ongoing or just isolated?
If Isolated to the area shown, I'd guess that it is just a matter of the leaf taking a little damage when you topped it. It doesn't take much to cause damage to the leaf when they are just forming, and the damage becomes very noticeable as the leaf grows. Just a wild-ass guess, but you say you see no insects, and it certainly *doesn't* look like a nute issue.

[randomking]

dont forget some bugs come out at night to munch on the leavs then hid when lights come on