It's possible, but probably not. They may not have gotten the timing right. This happened when I had my timing belt replaced last year. Contour timing is very sensitive. You might want to take the battery cables off for about 15 minutes to half an hour, let the computer reset itself. If that CEL comes back on and it's the same code, then the place your timing belt was done didn't get the timing quite right most likely. That's what happened to me. Take the car back and make them set the timing again.
Also, I don't see why Auto Zone couldn't reset the CEL. That's odd. Every Auto Zone I have been to has asked me if they wanted for them to reset my computer after they've checked it.
Good luck