Our rail-riding spies spotted some familiar faces on Amtrak’s Acela Express last week. But the homebound Members were traveling under very different circumstances.

The tipster was trying to get situated on the express train to New York when, lo and behold, they noticed Rep. José Serrano (D-N.Y.) doing the same. And then they stumbled upon Rep. Jim Himes (D-Conn.). Heck, they even saw “Meet the Press” host David Gregory.

When everyone began taking their seats, Serrano settled into first-class (along with Gregory), while Himes hunkered back to business class — it was not at all what our tipster expected, given that Serrano represents the rough-and-tumble Bronx and Himes hangs his hat in tony Greenwich.

Serrano insists the upscale accommodations were an anomaly, stressing that all the other seats were sold out during that particular trip. “I hardly ever go first-class,” he assured HOH.

A Himes aide said the Congressman never travels first-class. But he’s not afraid to treat himself to a relaxing cup of hot tea or ice-cold beer — “depending on his mood,” the aide suggested — during the long ride home.