messaging an old friend

i was friends with a girl when we were 4-9, then sort of lost touch as we got older. we still had a little bit of contact up until around 4 years ago, when she moved to a private school about 30 minutes away. recently, our mums met at a pub and apparently this girl is moving to my school for sixth form. would it be weird to message her and say hi, as i know that she wont have many friends when she moves here. thanks!