Head Coach Lovie Smith has always kept injury updates vague and close to the vest, but if Forte's injury is significant (which high ankles can be), look for that news to spread pretty quickly.
Forte had a very public dispute with the team after the 2011 season, where he wanted a long-term contract commitment that the Bears didn't seem to be open to. At one point, the two sides were not even close on the money, but right on cue, Forte got his extension without missing any camp.
Rumors had it the Bears were worried about Forte's knee, but so far, that doesn't appear to be part of last night's injury. More news and updates as it develops.