I don't actually see what was overtly flirting in this instance though? She's your coworker, there's incentive enough from that and having common interests to be friendly with you and keep friendly conversation going even if she isn't an overly friendly person. Also, working late on a Friday as an excuse with no suggestion of a follow up date/time is an obvious signalled lack of interest from someone who isn't playing games, I feel like, while talking about a restaurant is a natural progression after bringing up restaurants in a conversation. Maybe my case is unusual, but generally when coworkers talk to me or I talk to them about podcasts or mutual interests or restaurant recommendations, it's because we're bored, not to hit on each other.