Why would that be weird?
Is it weird that I have a retired teacher as a best friend?
no weirder than i have a retired cop as a friend
Nope not at all.
YES ... All teachers are supposed to be "put down" within 3 months of retirement.
If you're young enough to use "weird" in that context then I will say it's a little unusual. It's good to have an older friend but as time goes by you'll make more friends in your own age group -- hopefully without losing your current best friend.
When I first arrived my cat was mine.