I agree with Mike_no. I will say, however, that any 'odds' or chance are quite low at less than 2 percent. Worst case scenario, less than 2 %. Very unlikely is what that means.
I don't think it's wise to calculate a probability in this case, it's possible that you may be struck with lightning when you step outside tonight, you don't calculate it's possibility each day, right?
You don't know the HIV status of this guy, every one around you is not positive. No point in being paranoid, just get tested at 28 days from the date of your exposure with a IV Generation HIV test.
Also, try and reach out to this fellow and simply asking him, people usually don't lie when asked directly.