No. The only anti-air missile that could reach that height not only is deployed in fixed sites around Moscow, but has a nuclear warhead (which would not only have been instantly noticeable but would have blacked out half of Texas from the EMP pulse). Also, as others point out, such a missile would be clearly visible, and no such contrail was.
or a reentry-trajectory just a fraction of a hundredth of a degree off, set by a "deep mole" in Houston?
Only slightly more likely. Right until the moment that contact was lost, Columbia was on track. For several minutes prior to loss of contact, however, various sensors in just the left wing either failed or showed an overheat.
Did the Arabs dance in the streets?
Just the Iraqis (so far).
I respect the fact that the tolerances are pretty tight for the angle of re-entry, but I don't see how they could be that tight.
I am betting that the official inquiry will eventually conclude that the tiles on the left wing were damaged.