I think this is pretty common. It isnt called Delayed Onset of Muscle Soreness for nothing. After a heavy work out the first day I am sore, next day I am really sore and stiff, 3rd day is somewhat like day 1 and after that the soreness slowly dwindles and is gone completely after a week. Of course this only happens when I work out for the first time after a lay off or new cycle or after hurdles jumps in the evening with lots of short sprints and a PR work out on DLs and Dips in my 5x5 cycle.