Eggcessive - you might just be right about the leg coloring. I checked earlier pictures I have of her from a couple of weeks ago and the spots are in those pictures too, so they've been there a while. I also got word back from the breeder I bought her from and he said the same as you, just pigment, and that they're common on Barred Rocks. I just don't know why I didn't notice them before since I check them over thoroughly about once a week. I must be losing it in my old age. I also read some info from an old book I have that was written in the 1906 (The Plymouth Rocks, Barred, White, and Buff) about how pure yellow legs are desirable but that oftentimes spots occur, and how you should select against it if possible. Supposedly spots are a defect but way on down the ladder behind type and coloring. It also says that males with only a few spots on their legs will often produce females with many more spots, so you should only breed from males with no spots.
So anyway, in summary I'm concluding it's nothing to worry about and par for the course with Barred Rocks. I'm still going to apply castor oil just as a preventive measure, and maybe I'll do that with all of my SOP birds, but apparently it's common and harmless. The other conclusion I guess is to make sure we always check every part of our birds when doing a checkup, and keep detailed notes and maybe a good picture in case we find something we didn't notice before.
Good to know the mystery is solved. Pigment spots. I've never had any of those...yet...but now I know.
LofMc