We bet she wishes she was still frolicking with her boy toy!

Kourtney Kardashian is back in LA and back to parenting duties following her sexy birthday/anniversary trip to Utah with boyfriend Younes Bendjima, and she couldn't resist planting a smooch on son Reign while out running errands with the kiddos yesterday.

While she was away, baby daddy Scott Disick and his lady love Sofia Richie looked after her brood, and it sounds like the mother-of-three has come around to the idea of the teen model playing stepmom.

"Sofia is helping Scott be a better, healthier person. Kourtney feels confident that Scott and Sofia takes good care of the kids. Scott is a great dad when he has his life together," a source dished to People.

Still, the reality star feels Lionel Richie's 19-year-old daughter isn't an age appropriate choice for her ex. Isn't that the pot calling the kettle black? Younes JUST turned 25-years-old, and she's almost 40!

"Like most people, she thinks Sofia is way too young for him and doesn’t get it. Kourtney didn’t think it would last and she never thought Sofia was going to meet her kids. But now, Sofia spends a lot of time at Scott’s, so Kourtney allowed her to meet the kids," the source added.

In case you missed her vacation pix, you should really check them out!

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A post shared by Kourtney Kardashian (@kourtneykardash) on