Katy Perry and John Mayer were spotted on Monday getting flirty at a Memorial Day get together at the singer's Hollywood Hills home. Two months after their second break up the two reunited to celebrate the holiday and barbeque at the "Fireworks" singer's brand new home.

The reunion between the stars may signal a second chance at romance, an observer told Us Weekly that "They seem to be back together -- or back together-ish."

Mayer,35, and Perry, 28, were spotted getting quite cozy at her soiree, "They were very flirty and having a really good time together. They have good chemistry."

"They were definitely friendly," a second eyewitness said of the former couple.

Back in March, following their break up, a source told the magazine "It's not over until it's over."

"You have to see how things play out."

Us Weekly reported that other guest who attended the singer's party on Monday's included "Girls" star Allison Williams, along with her boyfriend Ricky Van Veen (the couple double dated with Perry and Mayer at the Grammy Awards back in February), Mindy Kaling, BJ Novak, "2 Broke Girls" star Beth Behrs, "Raising Hope" actress Shannon Woodward, and much more famous faces.

The couple first split in August of 2012 after casually dating but rekindled their romance in September. The fire then flamed out once again and the couple called it quits for the second time in March.

Perry was spotted the day before with another Hollywood heartthrob, Robert Pattinson, the two were seen crashing a wedding rehearsal over the weekend.

The two have been friends for a long time but now that the actor is single after dumping "Twilight" co-star Kristen Stewart, many are beginning to wonder if there is more than just friendship going on between the two.