not necessarily, with the over /under grip the under hand and the bicep are under tremendous strain which can cause it to rupture.
Though the fact that its happening only at higher weights means that you are using the bicep to pull for some reason. The bicep should have no involvement in a DL. Stability at most. It does not assist the grip. People try to keep their back and traps fully flexed (a good thing) but when they feel their form start to go they attempt to readjust their form mid-lift. That will certainly put a strain on the biceps. This is the reason it is always the "under" hand. There would be almost no chance of ripping the bicep if someone were to use straps (overhand). I suggest people use straps at max if they have had a problem with the biceps while DLing. Also work on static grip (holds).