Question Author
Yes I had thoughts about just asking her straight but I was always taught never to ask for money! Silly I know.
Come to mention it she has been a bit forgetful of late but not sure its that in this instance. She is usually pretty on the ball with money as in if I ever owe her money, even a small amount she remembers the exact amount to nearest £0.01. For example my little girl does ballet, mum offered to knit a cardigan and around the same time mum picked up some plants for my garden. I was about to give her the £40 I owed and she then said I owed her extra £2.78 for wool for the cardi!! I assumed that when she offered to knit it was a gift, and I didn't expect an invoice! But like you say I know for next time.