If the user is new to Stack Exchange, or has indicated that one of the answers has worked for them and has yet to accept an answer days later, a prompt of some kind is probably in order. In the case where the user is new to Stack Exchange -- For example if the user has never accepted a question (check their profile and reputation to see if they might be new-ish to this) -- then a comment on the user's question with a little explanation about accepting answers would be a good idea in my opinion.
