For Memorial Day 2013, Katy Perry kicked off summer with a few good friends -- including John Mayer. Two months after their second breakup, the "Shadow Days" troubadour, 35, was among the guests at Perry's brand-new Hollywood Hills home on May 27 for a barbecue bash, Us Weekly can confirm.
Whether the reunion signals a full-on reconciliation for the pair remains to be seen. "They seem to be back together -- or back together-ish," one observer tells Us of Mayer and Perry, 28. "They were very flirty and having a really good time together. They have good chemistry."
Adds another witness: "They were definitely friendly."
Other revelers for Monday's party included Girls star Allison Williams and boyfriend Ricky Van Veen -- who double dated with Perry and Mayer at the Grammys in February --- plus Mindy Kaling, BJ Novak, 2 Broke Girls' Beth Behrs, Raising Hope's Shannon Woodward, plus actresses Kate Micucci and Riki Lindhome.