I had not put that little 2+2 together about Colin -- I hadn't forgotten it, but I hadn't put it together -- good pickup.

I'd read in Time that the publishing company actually hired a continuity person to make sure that kind of thing didn't happen. oops

Although, I guess (with a huge stretch in my guessing) that Colin could have sneaked in somehow once he found out that the fighting was going to start or had begun.