Miranda Lambert's Keeper of the Flame Tour openers were already on stage, but she felt she needed one more voice to help her with a Janis Joplin cover in Bangor, Maine on Sunday night (Aug. 21). So, Lambert brought boyfriend Anderson East to the stage.

"Hold up, we're missing a singer," she told the rowdy crowd, stepping away from her mic to grab East by the hand. "This is my boyfriend, Anderson East, y'all."

It was one of very few times Lambert and East have shared a stage, and unlike stops on his tour with Chris Stapleton earlier this year, they didn't do much dueting. East just enjoyed the vibe as Lambert, Kip Moore, Gwen Sebastian and Brothers Osborne did the bulk of the singing of "Me and Bobby McGee."

That group tore through a cover of Linda Ronstadt's "Willin'" just moments earlier. "Willin'" is a song Lambert has been covering frequently during Keeper of the Flame Tour stops, and the group seemed to be well-rehearsed as they played it for fans at Darling's Waterfront Pavilion.

The impromptu East appearance capped an eventful weekend for Lambert. On Friday, she broke down during "The House That Built Me" when a soldier held up a sign thanking her for being the last voice he heard every night during his tours overseas. The next day a 6-year-old fan proposed marriage, and she said yes, even though it may be awhile before that's legal. It's possible East may have been on hand for one or both events, but evidence only confirms he was in Maine on Aug. 21.

The "Vice" singer's Keeper of the Flame Tour continues on Thursday night in Columbia, Md.

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