This exact thing happens to my Fifth Avenues, on my right foot only. It is because my right midfoot is larger than my left -- specifically, the base of my 5th metatarsal bone protrudes over the edge of the insole, pushing out the leather of the upper. This occurs for me on the Allen Edmonds 5-65 last, which is (in their words) "best for a long, narrow foot." This last does not fit me properly, as I do not have a long, narrow foot. It will not fit me in any size. I have had some degree of problems with my stupid protruding metatarsal bone with every one of AE's lasts, except for their 3-333 last which fits me perfectly. Here are some photos:
Right foot, showing significant bowing.
Left foot, showing negligible bowing.
Both shoes, for comparison.
Wearing Superfeet 3/4 inserts (or some other insert) raises my foot up off of the insole and helps with both bowing and comfort, but I doubt that you would have room for them judging by the lace gap that you currently have. Good luck trying to fit into the 5-65 last. It's not for everybody.
Edited by coldsalmon - 8/1/13 at 6:44pm