Same thing happened to me, I bought a yaizmat head and he sent me the texture with his signature on the bottom of it. Never thought too much about it though. The sigs are not really intruding.

sigs at the bottom of a head are perfectly normal since it doesn't affect the head texture much or at all
most people would watermark by drawing barred lines diagonally like the image pimp provided

did anyone ask 13chillz

he's inactive
anyway this has been resolved awhile ago p sure this can be closed

I think it can indeed. Closing. You can reopen it you'd like.