IMO a "tease" should be reserved for something where it is fairly clear that the band intentionally played a piece of another song, or maybe unintentionally stumbled upon it, but then recognized it and continued with it. A tease could exist even if they don't nail it note for note, because they're up there without a net and don't really have the liberty to run through it a few times or pull up sheet music.

Mind-reading for intent is clearly a high burden of proof, so this is an exclusive group, reserved for really obvious instances.

I feel there is room for a second category. Where intent is less conclusive or maybe non-existent. But the band is playing a riff or progression that sounds a lot like something else. I think having a category like this would be useful to many dotnet users and other fans who might not care to get hung up in a binary discussion of "Is this a tease or not?" (in a lot of cases we can't really know without asking the band after the show), but might want to recall a show or recording when they played the riff that sounded like "Single Ladies" or "Roadrunner", for example.

Whether or not it was intended as a tease, a lot of people can and will agree there is a similarity. To me, that is useful information. (Insomuch as any of this nerdery is "useful." )