I read yesterday that NASA is sending...
an ex-Astronaut (probably one with a physics Ph.D) to investigate the photo. They have not ruled anything in or out at the moment.
If something like that did strike the Shuttle, it sounds like a truly freak occurrance. We've been launching and reentering objects for over 45 years and so have the Russians. To the best of my knowledge, nothing remotely similar has happened before. Of course, there's always a first time.