I had gone on my first run in months last night, and aside from the expected soreness in the legs and calves, I've got a rather sensitive spot on my abs, about an inch down and left (from my perspective, looking down) of my navel. I wouldn't necessarily call it pain, just abnormally sensitive. The rest of my abs are slightly sore, nothing that like this little button of 'ow'.
Some background: I used to run pretty regularly, not marathon level, but upwards of 5 miles a day. Last night, I ran just over 2 miles at a slow pace of ~11 min / mi. Just trying to get my legs back under me.
Any ideas as to the cause of the pain?