Morning all and Happy Thanksgiving. I'm a new 8A operator. Doing our first conditional check and noticed 100LL stain on the lower left side aft of the fuel tank at the access/inspection door. The inboard left inspection panel. Zero drips on the floor for the entire time I've had the airplane (1yr). A few instances of the line guys overfilling and fuel draining onto the leading edge of the wing (with a likely flow under to that access panel area). Before I pull the whole wing apart any other thoughts? Any thoughts or insights on troubleshooting before disassembling the wing would be appreciated. Pic attached.