Details sketchy, but it's blowing up on Twitter. I'll add more as more is known.
h/t Kerns for the heads up.
Update: Rotoinfo.com reporting it's a hand injury.
Update #2: Pete Prisco of CBS reporting it has a hand or finger injury. Not sure if this is fresh info or the same stuff from above.
Update #3: Multiple reports AJ came down on his hand awkwardly. We should find out more after practice. Also, for the record, I can't wait to have a "BREAKING: Houston Texans Win Super Bowl" post. That'd be much more fun.
Update #4: Doubts about the "carted off the field aspect."