Just picked up my first AK variant, also my first semi-auto.  So here's the problem.  

When I fire a round the rifle cycles, ejecting the brass and loading the next round.  

The problem is that the hammer gets caught by just a hair on the reset catch (don't know the technical term for the part).  

I can remedy the problem by flipping my finger behind the trigger and pushing it forward, then I get the 'click' of the hammer moving into the correct position.  

The weird part is that this does not occur when I cycle the rifle by hand, so I'm unable to replicate the problem by hand, only by firing the rifle.

Any ideas of what the issue can be?  I was thinking it might have something to do with the trigger "return spring" (another term I'm not sure of), but like I said, my first semi-auto.

Thanks in advance.

Thought I might post the solution for anyone who ends up with the same problem on the same gun.  

It turns out the control rod that goes from the trigger to the fire control group was ever so slightly bent near the magazine well.

This caused there to be just enough tension that the trigger wouldn't reset.

I took the gun back to the dealer I got it from and he fixed it for me under warranty.

Hope this helps someone.