It was only when she was reading the pattern to add the tassels that she noticed which house she was knitting for, and it confused her a little. Here's pretty much how the conversation went:
Mum "I just noticed this scarf is Slytherin"
Kel "That's right"
Mum "But Harry is in Gryffindor isn't he?"
Mum "Shouldn't the wool have been red and gold then?"
Kel "No, because then it would be a Gryffindor scarf"
Mum "But that's the house Harry is in"
Kel "Yes it is"
Mum "Then why did I just knit a Slytherin scarf?"
Kel points at Slytherin banners on wall
Mum "But why all the Slytherin stuff, Harry is in Gryffindor"
Kel "But I'm in Slytherin"
Mum stares blankly at me for a while "I thought Harry was a Gryffindor"
Kel "He is. I am in Slytherin. Slytherin is my house"
Mum continues to stare blankly, quite clearly not getting the concept before wandering off somewhere
Perhaps I should really confuse her and have her knit a Ravenclaw scarf for bardiphouka. She really is a fantastic knitter. She makes baby clothes usually, and just gives them away to people who need them.