Yes, take her to the doctor. I don't want to freak you out because I am certainly not a doctor, but I know Hogkins Disease (a canger of the lymph nodes) can start out that way. I don't think a swollen lymph node would move that way.
My son has many of these lumps in the same area and has had since birth. All of them are pea sized and they also move when touched. I have taken him to a pediatrician and he has confirmed they are in fact lymph nodes. He said that they are normal and not to worry
Hope this helps
It sounds like it is a lymphnode. I have had the same thing for 28 years and it is nothing. NOw my daughter had an infection in her lymph node however it turned out to be the size of a golf ball and was accompanied by a fever. I would get it checked out for your sanity.
My son (now 7) had these lumps in his neck and groin - small, moved around, pretty much like the one you described. We have Hogkins disease in the famaily, so the surgeon removed them to send for hystology. It turned out that he has an "over active immune system" and although he didn't seem ill, his body thought he was. Apparently you need to worry if the lump grows, causes pain or become immoveable. Let a dr check them out with her next checkup, but personnaly (having been there) I don't think you should worry.