I just finished building a Mill Creek 15 and launched her yesterday. I took her out for a few minutes today then brought her back in. When checking over her an hour or so later, I noticed a discoloration radiating from the stem in the stern (where the side panels are joined together). It's slightly larger than a quarter on one side and twice that size on the other. It's grayish, like a bruise. I put two layers of fiberglass in that area, epoxied well, and it has 9 coats of Epifanes wood gloss/varnish on top of that. Any ideas?

Thanks,
Jenny