My First Time With A Gym Buddy

I'm new to working out and going to a public gym in overall. I've been there for 2 weeks now. The men showers are shared but with small cabins with protected glas (you can see through it pretty much though). I wasn't used to it but decided to try it after one of my work. There was a guy in his 40s who i saw running around all the times helping folks out with their equipment. Yesterday I saw him in the shower and was a little embarrassed so i ran naked into one of the small spaces, but never locked the door behind me. I could see him approaching the door, when he ask if it was okay to enter. I told him it's fine, while being super insecure of another man seeing me naked. He grabbed me and pushed me against the wall, telling me "boys like you are born to suck". He started kissing me, then pushing me down to suck his dick until he came.
I loved it, we almost didn't speak at all and it happened so quickly.
I'm so unsure to go there, because i wanna tell him that i enjoyed it and would love to do more....
But i'm so insecure about that...