In a word, yes. The longer version is that BtVS is a piece of postmodern art because:
"In terms of popular culture and mass media, there has been a large push towards the postmodern tendency of "bricolage, pastiche and intertextuality" (Altman, 1999:141) in recent years. In regards to BtVS, the series creator, Joss Whedon, has stated when he was forming the character of Buffy he thought of "the little girl, the little blonde girl who goes into a dark alley and gets killed, in every horror movie. The idea of Buffy was to subvert that idea, that image, and create someone who was a hero where she had always been a victim. That element of surprise, that element of genre busting is very much at the heart of the series" (2001). The notion of "genre busting" is found in the postmodern mixing of horror, comedy and drama, and results in the playful deconstruction of genre conventions, forcing the audience to question their assumed knowledge of the 'rules' of a particular genre, such as the formal repetitive structure of horror films (Dika, 1987:87)"
Therefore, the primary reason why the show can be considered postmodern is that, from its very inception, the show was intended to flip and subvert the horror movie standard of the blonde girl being slain by the monster in the dark alley.
BtVS also goes on to subvert standard readings of text and narrative by becoming extra-textual or outside of the text, by making transgressive allusions and references. Buffy's postmodernism comprises not only self-awareness but also awareness of other shows, movies, books and anything else, including referring to Martha Stewart as a demon.
Postmodernism also often defines itself by what it is not. In the case of Buffy, the show (and its creator) often defines itself by setting itself apart from something else. Thus, for instance, in Buffy many episodes, scenes or lines start with a cliché and then move on from it to subvert that cliché or exaggerate it in unconventional ways for dramatic purposes. This is demonstrated most clearly when a character questions a commonly used saying. For instance, in the season 2 episode, 'Lie to Me', Willow wonders why people say 'sticks out like a sore thumb' :
- Xander: In no way do we stick out like sore thumbs.
- Willow: Okay, but do they really stick out?
- Xander: What?
- Willow: Sore thumbs. Do they stick out? I mean, have you ever seen a thumb and gone, 'Wow! That baby is sore!'
- Xander: You have too many thoughts.
Another example is the show's original conceit: the cliché that high school can be hell is given a postmodern twist by creating a show in which high school was literally on the mouth of hell.