After a couple of days invite him to a social gathering, stop trying to be macho because he can sense it anyway. If he agrees to come, there is a tendency that he's interested. Talk to him and make simple gestures like getting him his beer or reserving him a seat. Make sure you are observing his responses as well. You will know if he is into it or if he wants to get that running shoes to stay away from you.
If you feel that he is comfortable with all those 'sweet' offers that you are doing. Then, I am not stopping you. Proceed doing more advanced actions. Perhaps, you can invite him over to your house and watch a couple of movies. Flirting is not all about winking of the eyes or exchanging chessy messages... Let me remind you that we are dealing with mature straight guys and not the jocks from your senior years.