Is Justin mad about Sel's kiss with Nat Wolff?

Wowza- the M staff all had a collective "OMG" face when these pics surfaced of Selena Gomez happily kissing Nat Wolff from The Naked Brothers Band. Sure, they were just filming a scene for their upcoming 2013 flick, Feed The Dog, but what would boyfriend Justin Bieber think of the ultra flirty scenes? While Justin did avoid set that day he went to the studio instead sources close to the couple insist that JB had no problem with the smooch. After all, it isn't the first time in their relationship that they've had to deal with this- Selena stood by as Justin kissed a girl in his "Mistletoe" video and Justin also watched Sel kiss a costar in Monte Carlo." Actually, Justin was pretty cool about it," Selena said of the kiss in Monte Carlo. "I was impressed." Phew-we're happy these two are drama and jealous free! As for Nat and Sel, they're just buds and are excited to play love interests in the flick. And getting ready for the big kissing scene with Selena was no sweat for Nat. "I just chew lots and lots of gum!" he dishes to M. LOL!