Generally speaking, sober folks want support and encouragement.
You don't have to abstain from drinking all the time, but refraining from imbibing around them is always appreciated.
I'd had enough embarrassing nights out; I'd woken up beside more than my fair share of unattractive strangers, and was, in turn, more than ready to bid farewell to the drunken rants, crying jags and battles with lovers, friends, cab drivers, cashiers and waiters.
I also thrilled at the notion of never having another hangover.
If s/he does notice—or if you feel uncomfortable with your date drinking around you—you have every right to cut the date short and walk away.