maybe he was late for the train, coming from the direction of the driver, so he tried to get in there but didn’t so then he went back a couple cars for the next one a couple back.
or maybe the dog actually has a problem, and he was actually carrying it for some reason. I mean I didn’t see enough to know if that was the case and so he wasn’t doing it to be sneaky, and not approaching it with a sneaky mindset - seems like a longshot of course.
or maybe he has gotten let on before and nobody has complained, maybe it’s like hereabouts where it’s not allowed to bring coffee on the bus but nobody says anything about it and then I had three drivers in three days that wouldn’t let me on the bus for carrying one. In which case I’d think that driver was an over-officious jerk.