This could mean a variety of things - an injury, a clothing or equipment issue or anything.
This post from the Frayed Laces blog shows how small adjustments can make a big difference riding your bike. The writer uses video to show how a minimal tweak to the bike made a big differencebased on some shoulder discomfort she was experiencing.
Taking your bike in for a tuneup early in the season or just having one of the experts take a look at your fit is probably a worthwhile trip . . . particularly if you've noticed something you don't like.
Going to take some time off from posting for a bit for the holiday.