I need advice on a weird situation and what I should do.

I have an ex-girlfriend (i am also a woman) and we've been separated for a year now. She has blocked me on everything but we still follow eachother on instagram - fair enough, she needed the space and time to move on and I respected that. We haven't spoken in a year. The other day I was out and we bumped into eachother. She was very emotional and we had a quick chat (we both still have feelings for eachother). She then grabs me and KISSES ME but I had to leave as I was late to a thing and rushed off. This will probably not be the last time we bump into eachother and I don't know if I should send a message and talk about it?? Or discuss boundaries??