vaccinated twice??

Hello, my son was vaccinated for chicken pox at around 10 months old in the United States. ( He had a slight reaccion 10 days later they said was normal, just two or three little pox on his face, nothing really)
We live in spain now, and he has had his 11 year old pediatric visit, and if a child has not had chicken pox by then  , they vaccinate. I menitoned my son was vaccinated at 10 months old.
The pediatrician suggests vaccinating again, since he was vaccinated so young and his defenses may have gone down, we shoudl think abou t this, she is not saying it is a must, but she would do it, but letting us have a think.
She thinks there is no harm to this and would be like a booster vaccine.
PLEASE TELL ME WHAT YOU THINK!!  I think she is a very good doctor, but REALLY WANT A DOCTORS OPINION FROM THE USA!!! THANK YOU!!