I know Amtrak has lowest priority on most of the tracks it runs on, and sometimes ends up having to stop and let freight have right of way - possible something similar going on?
Every time I've been on an Amtrak train we had to do that at least once. I'm not sure we ever stopped between stations for any other reason, actually; obviously accidents happen and everything, they're just vastly outnumbered by "this service exists at the sufferance of Norfolk Southern" incidents.
