Rough print on one side (no replies)

I have noticed for awhile that parts I print lately tend to be a little rough on one side, it did not bother me really but today I printed a flat plate that had 2 posts sticking up 90mm apart and the one on the right printed good with just a very minor roughness on the left side, but the post on the left printed very, very rough all around. Unfortunately I filed it down before I thought about taking a photo to post here.

My belts are tight, my bed is level, I don't have any significant Z wobble (at least not that I can see). Any ideas what causes rough printing on just one side of the printer?

Thanks!