But all was forgiven and forgotten not long after the spat had begun.
Gaga and Calvin? This we would love to hear.
[Related Story: Lady Gaga does a Justin Beiber and throws up on stage]
[Related Story: Kelly Osbourne: Lady Gaga is pregnant]
An angry Lady Gaga however quickly took to Twitter to deny Calvin's claims.
She posted: "never even emailed you @calvinharris I guess it's hard to believe I write + produce my music. cuz I'm a woman I don't know about EDM right?" [sic]
Flippin' heck, Gaga was clearly not amused.
Replying to the hot headed singer, Calvin Harris explained that he had in fact received an email from her management and that she had got the wrong end of the stick.
He wrote: "@ladygaga no your label emailed me. I always make sure I say Im a fan when asked about it, I apologise if I offended u, wasn't the intention." [sic]
Lady Gaga then responded again to thank the DJ for his apology, also apologising in return for her outburst.
She posted: "@CalvinHarris thanks for the apology &explaining. My apologies too. Congratulations on your album. Wish you well. Cheers." [sic]
Well it's nice to see celebs acting like grownups for once.
The cast of TOWIE, take note.