Just being aware is the most important thing 
You did well not to suggest turning her phone off....she can think of that one by herself 
Instead, just listen and share her concern. 'Trouble is, everyone just wants to wish you well, and they don't think that loads of others are doing the same!'
Sometimes, when people have a 'problem' they don't want suggestions, however brilliant, at solving it. They just want someone to listen.
If you really do want to suggest something, then pehaps you can phrase it like this, 'I wonder, would it help if ....?' and not 'well, maybe you should.....'
Enjoy being a grandmother. It is one of the greatest joys in life.