Should my ears still be ringing a full day after a concert?

Possibly. Tinnitis is becoming a more frequent problem among the younger age groups, for a reason like this, that they often attend loud music events, like rock concerts. Many younger people carry musical devices around and they have ear phones, and attachments so they get all the music, no matter how loud it is. Therefore, it is strongly possible to have tinnitis (ringing) a full day after a concert.