OMG! John Mayer is REALLY making the rounds!

An inside source reveals exclusively to X17online that John Mayer and Jessica Simpson had lunch in Calabasas earlier this month! The duo was very careful not to be seen, and the source tells X17online, "Jess and John looked so happy to see each other, and it looked to me like they were more than friends!"

What is going on here?! Would Jess dump Tony for John, or is she just being a great flirt friend to the newly single singer? And what would Tony think of this?! Think the NFL quarterback is scared of losing his lady to John?