For 28 years, it was a holiday tradition for Darlene Love to perform her signature hit “Christmas (Baby Please Come Home)” on David Letterman’s late night shows, but that all came to an end when he went off air in 2015. Now, they’ve reunited for Letterman’s YouTube channel to pick up where they left off.

Before Love sang “Christmas” with accompaniment from Letterman’s longtime band leader Paul Shaffer on piano, they all had a chat about the tradition. Letterman also asked Love about recently performing the song with Cher during the Rockefeller Center tree lighting special.

This prompted Love to air out her feelings about never being asked to play the song solo for the annual ceremony. “Do you know they wouldn’t hire me for that?” she said, noting that other artists have performed the track instead.

Letterman responded with disbelief, saying “That’s bullshit, and I...