Records is one of our areas so it bothers me when someone messes around in this category but if I understand the time frame, the sale basically occurred just before the weekend and like ladyisobell pointed out, some people step away for the weekend. (I need to do more of that with 5 heart attacks on my record). If they still have not responded by today, they are late. (just my opinion, now)
The learning experience in this is that sellers who take their weekends seriously or are truly 5 day a week sellers, need to explain that in their listing. (not that all things are read, but...) both within the listing and in the comments section eBay provides about shipping.
If it is an unusual weekend out, they could put the listings on vacation mode and specifically state when they will be handling orders. A Word of Caution: this is a good reason to NOT say too much about your location. Nothing better than to tell the thieves in your area what you have in your house and when you will be away.
We took a long weekend last week and put our store on holiday Thursday night. Any sales that came in Thursday would normally mail, but true to "Murphy's Law" we got a sale late Thursday night that had to be made. We immediately wrote to the customer and let them know it would not mail until Tuesday and we would pay the increase for the next faster shipping method OR we could refund their money immediately.
The customer must have placed the order, paid and gone to sleep, so we did not know the answer before we left on Friday morning. We got it while on the road and she was willing to wait, so no problems.
But, some folks do not live online everyday nor have portable devices to communicate within 24 hours, so from a buyer or seller's side, keep that in mind. I know it is hot on your mind, but we have buyers who buy and then go on vacation. In fact one of our Australian buyers went hiking in new New Zealand for a week! The sale completed just fine a few days later.
We don't usually nudge until 7 days have gone by, but I know many of us who do so in 4 days. If you want immediate payment, mark that choice when listing. It cuts down on issues that might irritate you.
I could ramble on but I have scratched my teaching itch, so I'm gone.