It looks like the alleged feud between music stars Katy Perry and Taylor Swift isn't over yet, and their shared ex-boyfriend may be a big part of it.

Did Katy Perry Reveal Something That She & John Mayer Had In Common?

On Thursday, Hollywood Life reported that Perry was apparently not happy after the "Shake It Off" star reportedly mentioned Perry during her interview with Rolling Stone where she was not put in a positive light. 

"Katy's feelings aren't hurt, they are just confirmed that how she always felt about Taylor and things she heard about Taylor are true," a source told the site. "Katy thinks it is petty and stupid of Taylor to do what she did and doesn't want to go to her level and respond more then the tweet."

Katy Perry Reveals Something 'Emotionally Traumatic'

Perry tweeted something this week that could have been easily about Swift. "Watch out for the Regina George in sheeps clothing..."

There have been rumors going back and forth on what this possible altercation could be about, but it could have something to do with backup dancers. It could also have something to do with John Mayer considering that the two girls dated him at different times. Apparently, Perry heard bad things about Swift from her former boyfriend, which have the "Roar" star a bad vibe.

"Katy has had many talks with and heard stories from John Mayer about Taylor and she's convinced [the 'Shake It Off' singer] is a conniving b----, who is only out to benefit herself," a source said. "Katy dislikes fake people and she thinks that Taylor is the queen of fake people. Katy can read through all of Taylor's bulls---."

Tags: Katy Perry John Mayer Taylor Swift