Nanny here and I disagree that this is nitpicking. Loving the kid and being trustworthy are the basics of the job, not the high-water mark beyond which one is asking for the moon.
My concern would be that as your baby more and more becomes a toddler, too much stepping in and helping are going to be a big problem. As someone said, though, it could be that she is stepping in more when you are present because she wants you to see that she is actively engaging your child. I think it would be reasonable to take a wait and see approach, but if you did want to talk about it, you should be able to do so without it being a big deal. Have you never corrected her on any small matter? Perhaps now is the time to have an overall conversation about the fact that your baby is a toddler and will need more discipline versus just love and affection. You can start a general conversation about discipline style, House rules, etc. and build from there.