I'd be SORE too from a 5k at this point! I ran 3+ miles a few times while pregnant with DD and then a few times after, but my body would absolutely scream at me and shut down (couldn't do anything else for days, ridiculously hungry, etc.) every time. Apparently I can't nurse and run! I haven't even attempted any running this pregnancy, just walking. So go you for getting a good run in!!
I have yoga tomorrow, which I am absolutely loving! And every time we take DD to the park we just walk and walk and walk, following behind her as she runs around and climbs and splashes :) My legs actually end up sore from that too, since I rarely realize that I haven't stopped moving for an hour and half to two hours! Plus, it wears her out and she takes a long nap. Win-win!