When is it appropriate to ask someone about employment where they work? Read ye olde detailes, plz.?

Today I found myself casually talking with one of the higher-ups at a radio station that I’d like to work for (my background is communications/marketing/unskilled labor), and in the course of the conversation I found myself wondering if that were the appropriate time to inquire about job openings.

Odds are reasonably good that we’ll meet again – she shops where I work, after all. Should that happen, ought I to ask?

Edit: A quick search turned up that she’s the director of sales and marketing for the station.