The focus ring could be loose maybe so it might need repaired.
BTW, does the distance scale on the lens move once you start turning the focus ring?
16-35L, 24-70L II, 70-200L II, 100-400L, 50L, 85L II, 135L, 24TSE, 40, 100 macro, 600RT x 4
I have more photo gear than I need. The blame lies squarely with Canonrumors