I never stop thinking about people in the past. I even search out old elementary school people, and for me doing stuff like that is hard because I've moved back and forth across the country so many times. A curiosity about someone in your past doesn't necessarily mean one is interested in pursuing a contact, but in a given situation it might be, who knows.
I think that you need to evaluate whether your husband is interested in having something outside of marriage or not, on various other actions which will speak louder than just a name on a search engine, and your own intuition is the best pointer.