Well to be fair in the case of the store clerk small talk is literally in their job description. A cashier is supposed to try and “sorta” socialize with the customer in order to be friendly and the best way to do that is to make observations about “that” specific customer. In the case of Yuri the fact that she’s buying more would be a natural subject to comment about. This is further proven by how once she gives a response the clerk doesn’t push the issue. It’s not that they were being nosy it’s that they were basically giving proper customer service.