I heard the same story.
After the Adrian Wilson hit, Trent was concussed again, this time in practice, but it was the week after the Chargers game where he played so well. He appeared on the injury report but not with a concussion.
According to this story (if I remember it correctly) the Bills didn't disclose the practice concussion and Trent didn't miss any games. He was subsequently concussed a third time in the game against the Jets.
So according to this story from an insider, he suffered 3 concussions within one months time.