[shut the front door]

We had someone out to clean our ducts last Monday (that's a whole 'nother problem), and he also cleaned the dryer vent for us. Ever since, the dryer gets plenty hot, but it is not drying the clothes. I've also noticed some lint coming on to the wrong side of the filter. I just figured it was lint that got stirred up during the cleaning, but why would it be sucked in, instead of pushed out?
As an aside, I will say that he did NOT go on the roof to check the exit end. He did everything from inside.
Any suggestions?