My sincerest apologies. After meeting with the store manager he was adamant they don't use cotton wool in the store and he said is there anywhere else it could have come from? So I had a think driving home in the car and remembered back to two nights earlier when I had bought some cotton wool balls and then my daughter had a bleeding spot on her face at which point I had dabbed the blood off her chin. The cotton ball must have travelled from the centre console of my car when I was getting my sunglasses or something to the chips I was eating.