The suspected bit of debris is certainly a grave concern. i'm sure millions will be waiting for word on what it was (if anything).
One thing to add, though, is that we will not have to wait until re-entry to find out if this is going to have any effects, because the Canadarm has
been fitted with a special 3D camera to inspect all surfaces on the shuttle craft before the planned return.
I've seen on CBC that the camera itself is a Canadian contribution and that makes me happy to be a part.
Let's hope it turns out to be no problem.

