There is the possibility that he didn't actually notice it beforehand, and was noticing another star? (if that makes sense
).
Do iridium's sometimes flare without moving in relation to the observer? I thought they just moved like normal satellites but were brighter at the peak of their travel? Anyway, he knows it wasn't a satellite. Since I've been into astronomy every time me and my mates are out in the evenings I always point them out, so they know what they look like
).