Its not personal.
Don't take it personally.
They are first time parents, that is her baby girl, and yes, she does get to have a say in things.
I also told my Mom, to wash hands before, how to hold my babies, what their cries/noises meant, what my kids as babies needed etc.
It was not personal against my Mom.
It was ME... as my kids' Mom, speaking.
I knew, my kids.
Even if I was a first time Mom, at first.
I KNEW my baby girl. (she was my first baby).
It does not matter, if they have never had children before.
This is their privilege... to be that Mom or Dad, they always dreamed of, before their baby was born.
Also, it is all in how you preface or say things/tips/advice to them, too.
But no matter what... it is the Mom/Dad, that have the last say, on anything to do with their baby or with their family traditions.
They have their 'own' nuclear family... to create too. This is their privilege.
To have and create their child, and to create their family, as they feel. They now have their own family and child.
Every family/parent, is separate.. yet, family. And a Grandparent is extra special. Yes. Of course.
But... really, don't take those comments personally.
It is not personal.
It is not.
Her Husband seems real proud of his Wife and as a Mom. That is really great. And him stating it, in front of others, to me means he is giving his Wife a compliment... to show her that he is proud of her.
That is nice. See it as such. It is not personal, against you.
You are the Grandparent. And there will be many many other instances, of them saying to you/others, what to do with their baby. This is normal. It is not personal against you.
They do not seem at all rude to you.
They already said they trust you and you all seem like a close family.
So be proud.
But heed to them because as you said, yes, they are the parents.
My kids are 4 and 8. I still, let my Mom know about my kids and what their routines are and what the rules are or not. And to wash hands too.
Sure. I'm a Mom. Moms do that. We can't help it. ;)
Don't worry.
You are Grandma and trusted and loved.
Don't take their comments personally.
They need to... be able to feel 'free' in letting you know, how it goes with their child. Its okay.
They do not at all seem 'mean' to you. They include you.