Is this guy just a rebound

So this guy I have has a crush on for almost 2 years found a girlfriend. And he’s deeply in love. Today I saw this boy walking alongside a bus I was on. He looked up at me and started grinning widely. When the bus stopped due to traffic he stopped and waved to me. He had dark hair, pale skin, and dark eyes and he was just so cute. His smile was adorable and he high-fived me through the glass window.

Idk but he was on my mind all day after that. Could he be just a rebound because I don’t want to lead him on or anything. Also, I know I’ll see him again because I saw him walk out of my school so I know we go to the same high school. Idk what to do about him.