John A , Mar 29, 2012; 09:37 p.m.
The only connection I know of between the back and the shutter mechanism is the little pin that activates the double exposure protection. If this is not free to push through, the shutter wont fire--back is out of align. I suppose that if it is somehow stuck or sticky, it could delay your camera firing--I don't know where in the process the mirror moves up. Anyway, maybe watch when you release the shutter and see if the little red indicator appears in the film count window right away or just right before you hear the shutter fire.
The other possibility is just that your firing mechanism is sticking--it rotates first to release the mirror and finally to release the shutter--maybe connected to the first issue.