I remember my first run-in with Tabata Squats - I had trouble walking down stairs for a week my quads were so sore!
If you just feel 'fatigued sore' then that's completely normal. You'd know if you were 'injured sore'. Like Peter said, it might be worth coasting through a WOD or two - going through the motions is a great exercise in active recovery. It's also good for you mentally to be able to turn down the intensity now and again - a lot of people burn out because they don't want to stop pushing themselves. Adequate recovery is just as important as working out.