We’re only four months into 2012, but it has already been a good year for Philadelphia folk-pop trio Good Old War. Their third full-length album, “Come Back As Rain,” was released on the Sargent House label in early March, and it debuted at No. 1 on Billboard’s Heatseekers chart. For the last several weeks, the band has been trekking across the country on a headlining tour in support of the album, and the road leads to a hometown gig at Union Transfer on Friday.

But the biggest thing Good Old War has done so far this year was to perform on “Conan” earlier this month, when Conan O’Brien’s other guests were “Parks And Recreation” star Aziz Ansari and Christina Hendricks of “Mad Men.” They played “Better Weather,” which, like most of the new songs, is a jovial and optimistic tune about love and friendship that showcases the trio’s warmhearted vocal harmonies. As it turns out, though, the band’s late night television debut was not quite as glamorous as they expected.

“I could create a story to make it sound cooler,” jokes drummer-vocalist Tim Arnold, who talks on his cell phone while the tour van heads toward Iowa for that night’s show. “Like, me and Christina fell in love, and Aziz and I were cracking jokes the whole time, but it wasn’t really like that. We arrived at 8 in the morning, sound checked and then basically sat around all day.”

Not that it completely lacked Hollywood glamour. “We did get massages,” Arnold continues, “so that was cool. Going into it, we imagined we’d be drinking cocktails, rubbing shoulders with celebs and hanging out with Conan. But I guess Conan’s a busy guy, because we didn’t really see him. Christina walked past me once, but there was no schmoozing outside the dressing room,” says Arnold, as his bandmates Keith Goodwin and Dan Schwartz crack up in the background. “But all jokes aside, it was an amazing experience.”