Ask what? I'm not acting like a teenager. I just plan on going to work out and I don't feel I owe it to him to find him at his desk. If he comes over to me, I totally plan on being nice. I don't mind going to say hi at his desk once in a while - I'm just not going to make it a daily thing.
I'm not looking to be friends with him. I just want to keep it amicable at the gym.
Ironically I mentioned that I was texting his old coworker (who I actually do like, but he doesn't know that). So if I say I'm enjoying my single life, he might say, well why does Brian have your number? I guess that would be childish on his part.
I think I'd be ok offering my email if he asks for my #.