It's difficult to say what is causing the "thumping", especially since you are unsure what part of the sail the noise is coming from. It could be coming from, as you suspect, the the leech of the sail, but in my experience that sort of noise is more often described as a "fluttering".
Does your sail have an adjustable leechline? Have you tried adjusting the tension on it? Most genoa leech lines will need to be adjusted depending on the wind speed and point of sale, generally needing more tension for higher wind and higher points of sale and less tension for less wind and lower points of sale.
If it's not the leechline tension, it could be as Charlie suggested that the UV cover is coming unstitched and flogging in the wind. But this seems unlikely given the recent vintage of your boat, and in any case ought to be fairly apparent visually.
The worst case scenario is that the sail needs to be recut, but that seems very unlikely, particularly if these are OEM sails from IP.
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Pacific Seacraft Crealock 31 #62
NEVER CALLS CRUISINGDAD BACK....CAN"T TAKE THE ACCENT