Well, checking on Google Analytics, I found the more precise problem, but I'm still stumped on what's causing it. The site was redirecting to the site appropriately, but pulling data for the main page from /cart/cart/... for the data, so something is causing it to put an extra /cart in there, but I've been searching for anything for a few days now that would cause this, and I don't see it. Thought knowing more precisely might narrow it down, but for me I still can't figure out why. I put the site back to how it was with the error, because I'd rather find the real solution, than to just side-step it with the other redirect, for other users that may run in to it.