The singer is worried that the stars will be aligned in the wrong direction during a segment of her 'Born This Way Ball' tour and sees it as a sign things could go wrong.
Between July 15 and August 8, astrologers say Mercury is going retrograde, which means it will seem to be travelling backwards through the sky.
"GaGa is worried as she wants the stars to be aligned when she hits the road," a source told The Sun. "She follows her horoscopes closely and has been looking ahead for when she's away."
They added: "She's a typical Aries - outgoing with a sense of adventure.
"But when she found out Mercury is likely to go retrograde, she wasn't happy and has been talking it through with her spiritual team."
Lady GaGa has added an extra date to the UK leg of her world tour. She will play a second gig at London's Twickenham Stadium on September 9.
The star has yet to confirm any dates for the North American jaunt of 'The Born This Way Ball'.
Tickets for Lady GaGa's 'Born This Way Ball' UK tour are now available here.
> Lady GaGa 'Born This Way Ball' UK tour tickets 'won't meet demand'
Watch the music video for Lady GaGa's 'Judas' below: