I think I already know the answer to this
but it's good to get others to tell it to me straight.
I had a ONS with a friend while away for a mutual hobby
(Ok, it's running.) Both single. I wasn't expecting it to turn into a relationship but, being honest, the sex was amazing and of course I was hoping it would happen again. 
Anyway, since the ONS, he has shown up at the running club only twice while I've been there. He says he's been busy with work recently. Fair enough. The first time he showed up, he gave me a smile and a wink but there has been no mention of what happened.
We had a 10 minute chat last Friday where he mentioned some things we were speaking about prior to the ONS but again, no mention of anything else.
He asked for a copy of the invoice we received from the hotel and asked me to just leave it on top of his sports bag. Which I did, but popped a little note in the envelope- "Lets not leave it too long to do this again!" (A bit cringe, I know!)
He hasn't spoken to me since. 
Hasn't turned up to any runs this week. Messaged a mutual friend to say he'll be back this Friday- I won't be there..
I've scared him off, haven't I?
He does have a demanding job but I think I might just have to accept that he's avoiding me now. I was hoping the note would break the ice and show that things don't have to be awkward between us but I think it achieved the opposite! Oops!