Thanks Mike. You have been most helpful.
I will contact them tomorrow and see if I can get them to say they were working in that area and might have accidentally caused it.
It certainly to me, doesn't look like a $2000 fix. I understand why they don't want to do it, as it's their liability, but like you said, it appears "muddy" down below the mark as if it had slipped or was loosened up recently and not placed back all the way back down to the original mark. Maybe they moved it while working on the motor to get it ready for spring, and didn't have it all the way back down revealing the problem/leak that might have been there for a while.
Either way, i'm taking it to a local marina place that specializes in gas tanks. Although they weren't too thrilled about working on mine if it had to be completely replaced or the floor torn up, maybe they will see this as a doable project.
The mechanic did tell me there is a patch for it, but he didn't want to do it. Doesn't to me, even seem like a patch is needed, just loosen the clamps, slide down to original mark, and tighten again, and then just keep an eye on them to make sure they aren't moving, or a leak somewhere else.