Go back to the shop that put it on. See what the mechanic says. Might just be that they didn't tighten the pinch bolt tight enough and the DR is coming out of adjustment or something else is amiss.

Since you said it was working good in the OP, I never checked the specs and such. I might do that later after I get back home. But off the bat, I'd say the mechanic is the one you need to talk to first.

Or is he not the one that put it on and adjusted it?