Thanks for the responses. If he asks again I'll try to be prepared with an answer of refusal.
He offered me a drink and I refused. I told him I don't drink anymore, so maybe he won't ask me again.
It is such a loaded issue - not only does it affect you but also the well-being of another. I mean, it's none of my business if someone else drinks, or is it? And alcohol is everywhere, but I don't have to stand in the middle of oncoming traffic, if you catch my drift. A lot to think about.
Thanks again