Generaly these are not a problem but you could check the following
1) When you fitted the lens, did you cock it first? If not the cocking lever on the lens fouls with the cocking lever on the body which stops the lens sitting squarely on the body.
2) Turn the body upside down and check that the lens panel has not been knocked out of true of the body. Both body and base of the lens panel should be square to each other at all sides, top, bottom and sides.