You got there ahead of us. I saw you there, but you looked like you'd already fallen asleep, so we didn't want to disturb you.

There were at least two conductors on the train (it's a legal requirement for a train of that length; also, they're the ones operating the doors and making the announcements), but they were not obliged to actually patrol the train. I don't recall there being any sort of intercom on Caltrain, so the only thing to do in such situations is to walk the train looking for one of the conductors.