Yeah, that's one of those hand gestures that's generally positive, but it's exact meaning depends on who is gesturing.
In WWII, it often meant, 'V' for victory.
In the 60's, at often meant, 'peace', as in part of the arbitrarily design peace symbol.
Now... I dunno. Ask the person doing it.
At least it's not as confusing and controversial as the 'okay' hand gesture that can also mean 'asshole'.
...or as nasty as the digitus impudicus, the raised middle finger.