Ready and waiting

My Mum rang at 10.25am on Saturday morning.
"Is that Lorraine?"
Yes.
"Is it you?"
Yes, it's me. (?)
"Oh, are you late?"
Late? For what?
"Church."
No Mum's it's Saturday, not Sunday.
"Oh, Oh dear. It's a good job I rang isn't it."
Should I be worried? Or is it easy to lose track of what day it is when you have no set routine?