I think there is. It's one of those things where if your partner knows you're just flirting, and nothing's going to happen (ie you're both secure in your relationship) then it's fine. It does go both ways - if one partner can flirt, the other can too.
My boyfriend and I are both VERY jealous people, so not for us! I understand that everyone's relationships are different, though, and that as long as those boundaries are mutual and agreed upon prior to flirting; good for them!