drunk dial etiquette question.

I received a drunk phone message a few weeks ago, in the wee hours after my high school reunion. It was a nice drunk dial--a strange and drunk compliment from someone who confessed their high school crush on me. And then copped to being drunk.

If someone drunk dials you and leaves a message, are you supposed to call them back?

Is is impolite to ignore their call, or a form of grace that you are willing to pretend it never happened?