Maybe he comes up in conversation frequently because he was a big part of her life at one time. I bring up exes too, but only in the context of talking about some experience I've shared with that ex, or something he'd told me back then that was relevant to the conversation now. As in, "Oh yes, that restaurant, I went there with Dave one time and we had these amazing profiteroles there...." or "I remember Dave telling me once that he knew the guy who makes those widgets and he didn't recommend buying them because...."
But if you're finding your friend says, "Dave likes green widgets too" right after you've said you like green widgets, then perhaps you might be right. I can't see the harm in asking her if she is trying to set you up, and if she says yes, let her know you're not interested. Or if she says no, "Oh that's good, because I'm not interested."