Okay, well, I took it back out shooting today.
I think this problem has something to do with my trigger also not resetting every once in a while. Not really sure what is going on there, but in the middle of trying to trouble-shoot it I was only loading two shells to see if the trigger would reset and allow me to fire semi-auto... Well, after loading two shells, I pulled the trigger once and noticed an unusually strong recoil. Looked down and the rifle was out... So it seems it did it again, though this time it was so fast I really didn't notice the double report.
Not really sure what I did, but after taking the gun down and checking out the action and dis connector, I placed the receiver as far rear into the stock as I could, and tightened down the screws. Afterward it was smooth sailing except for one time the trigger failed to reset again.
So I really don't have a clue what is going on... Everything looks okay. The only thing that looks abnormal is the buffer, it looks like the little circle in the middle has been collapsed into an oval shape...
Maybe I should just send it in for warranty work?