Okay. So I filled up the gas tank again today and made sure the doors were unlocked. Wha-la. It worked. The outside temperature was about 27 degrees and the access door slammed shut just like it should.
Tested the door locks and sure enough if the doors are locked the access door is locked also. What I don't understand is why the access door opened when one driver door was unlocked and the passenger door was locked.
So maybe, if one door is unlocked and one door is locked the access door will open but not close shut???
I dunno.
Just glad to have it resolved for now.