JOHN MAYER and TAYLOR SWIFT almost ran into each other at the Tower Bar in West Hollywood on Tuesday night.
--Taylor showed up at the place for dinner and was about to be seated when she noticed John eating with a friend nearby.
--A source says, quote, "Taylor very visibly . . . in front of the entire restaurant . . . demanded to be moved to the other side. The bar's usually an oasis of calm and privacy for celebrities and power players, but this was drama central."
(--There's no word what John's reaction was . . . or if he even saw Taylor. But the phrase "drama central" suggests that EVERYBODY in the joint was aware of the scene she was making.)
--Ironically, the next morning, "Rolling Stone" released the interview in which Mayer ripped into Taylor for writing the song "Dear John" about their relationship.