For all our readers out there worried about our dog...
Our vet could not find anything specifically wrong. And, much like Jeff and I, she had a difficult time deciding which foot she was limping on. (It really is a lot harder that it seems.) She did think that maybe she had a bruise on her foot pad, possibly the result of a little too much running. I apparently had overworked the poor dog, seeing as we did put in 17 miles in 5 days. So she mandated a little training break, and gave us some medicine to make sure her foot didn't get infected.
We also discovered that we have been bad dog parents, and allowed our pooch to get chubby. She had gained 5 lbs since her last check up, which is 10% of her body weight. We got a little lecture about not over-feeding and decided that maybe she'd had one too many table scraps.
As for her foot, she seems to be doing better. I even took her on a little jog (1.3 miles) this morning and she didn't seem to have any problems. Hopefully she'll be back to full runs soon. And it seems that shedding a few pounds may make the running a little easier.
I know it is for me.