When you say "below the zip" do you mean not associated with the zip at all, or maybe something to do with the stitching? I'd certainly get DUI to fix it, but if it's a stitching leak you can easily mend it yourself with Aquaseal. Apply it to the inside of the suit, not the outside.
I once had a DUI suit (made in England) and it was the only drysuit I've had that I wasn't happy with. To the extent that I sold it. I replaced it with a very heavy compressed neoprene suit made by a specialist manufacturer in England, and they don't have any warranty period as such - their suits are warranted for life. The difference between them and DUI was that with DUI I filled in the fitting chart and later received the suit, whereas with the "O'Three" THEY measured me AND there were three fitting sessions during the manufacturing process. Bit of a hassle getting there, but well worth it in the end. The price wasn't much different, but the quality was in a different league. The only snag with that suit is that it is REALLY heavy and there's no way I'd try to fly with it - I keep a trilaminate suit for that.