I had the same problem with one. The pic rails on ALOT of uppers are not held to very exacting specs. I tried mine on 4 different uppers and it was only satisfactory on one of them. I went with the RRA Dominator mount for the EoTech. This helped ALOT. It also moved the irons into the lower third of the field of view. You can also shim beneath the dominator. If yours doesnt lean too bad the mount alone will probably fix it.
I believe variance in pic rails is compounded by the variance in Eotech mounting blocks. I had a 511F that was crooked as hell on my AR, sent it to the guy I bought it from (reputable guy on another board) and he sent me a differnt one that fit fit fine on the same upper, so the the problem, in my experience, is on both sides of the equation.