Ya i believe that is low for a Hefe or any other beer. I would say that is why the flavor is not right. I'm not sure u can do anything to bring it back. Mashing that low doesn't leave any unfermentables for flavor or body. At least thats how i understand it. I didn't even think u would get a good conversion at a temp that low, but if u hit your gravity then I guess u did. Hopefully someone else gives some input on this matter. I've never mashed anything that low and can't say what the results should have been.