Shawn Mendes Out For A Hike With Rumored Girlfriend Dr. Jocelyne Miranda

Shawn Mendes really might be on the rebound ... because he was spotted out once again with his possible new señorita as they both got a lil workout in.

24-year-old Shawn was all smiles -- and shirtless -- on his hike with 51-year-old Dr. Jocelyne Miranda at Runyon Canyon Park in L.A. Monday ... chattin' it up as they got their sweat on.

Jocelyne was later spotted with a sweatshirt that says "I love you baby" -- and while people could connect the dots all day, it might still be too early to tell if this fling is legit.

For those unaware, Shawn's fans have been pinning the two as an item for a while now ... after being spotted together last year on a suspected lunch date, and have been seen from time to time since.

Of course, Jocelyne is a doctor to the stars and has decades of experience ... so it's still possible Shawn's simply just a patient to her.