Cracked nail?

Today when we were out training, Sadie (my FBL) started shaking her right front leg and "worrying" her paw...more specifically, one of the toes on her right front paw. I checked for thorns, cuts, etc. etc. etc. and found nothing. She didn't actually limp, but would occasionally stop to lick at the paw. We stopped the training session, went home and I checked the pads (and between the pads), the toes and the lower leg...all I could find is what looks like a crack in one of the nails about 1/16" out from where the nail enters the toe itself. It doesn't go all the way around the nail, but when I press on it she reacts...very mildly, but she does react, so I assume it has to be tender.

What does anyone do about something like this? Leave it alone? Slow up on her training for a while? Go to the vet? What?! By the way, we're going on a "field trip" to Baja week after next, and we'll be joined by some good friends with their FBL...and those two "girls" (who are also hunting buddies) love to run and play together.

Any thoughts and/or advice would be appreciated!