When I first got my 45 a few weeks ago, I noticed that it was tighter than my other lenses when mounting/unmounting it, but I didn't think much of it. It now has gotten so tight that I'm almost scared to put it on the camera for fear that it will get stuck. I'm not a small guy and it takes almost all the strength that I have to get it off. None of my other lenses do this. Has anyone else noticed this?