My 5 month and 2 weeks old baby boy is not rolling. I havent been worried about it and have been waiting patiently for it to happen soon for a few weeks now but it had not crossed my mind as a potential issue until today when the maternal and child health nurse came to see him today and asked if he is rolling and when i said not yet she kind of gave me a look. Anyway a while after she left, she called me back to check his book for his weight because she had forgotten to write it down for her records and so when i got the book i saw she had written and underlined not rolling in the comment section. Should i be concerned?