Gibson, 40, said she was surprised at the buzz from folks who were still fans of their heyday more than 20 years ago.
"We did a little promo appearance at the Canal Room in New York City and people just went nuts seeing us together, so we were like, 'Hmmm,'" Gibson told Parade magazine.
Gibson said she and Tiffany had previously kicked around the idea of a nostalgia tour. The idea has now taken concrete form in the "Journey Through the '80s" national tour, which will include duets and solo performances.
"I'm doing all my hits and also a big medley of my favorite 80s songs that influenced me," Gibson said. "I'm also doing a medley of my theater songs.
"When Tiffany and I were putting the show together, we were talking about how our influences are so different," Gibson said. "Hers are rock and country; mine are singer-songwriters and real pop people and theater."