Most likely there won't be an issue with the one stitch coming out after the 7 days mark. At this point the tissue is mostly healed and the stitches next to it should be holding the skin together. This is the scenario of the average pet. If you see an opening or drainage from the eye lids then I would bring him in because we don't want to trap bacteria in there and create a very serious infection. In the majority of cases an incision is healed between 7 and 10 days. I would do everything possible to prevent him from removing any further stitches or running his eyelids until all of the stitches are removed.
No problem. I hope that everything has gone well at the vet.