Is your paypal account still accepting payments? This has happened to me before on USA accounts when I hit the tax threshold. Once you reach a certain point you can't receive any more payments until you provide additional info to paypal.
There could be a chance that eBay just glitched out.
I've had times where I selected certain options in my listing but only to find they were not applied at all after saving them.
Have you contacted the buyer? Maybe he/she is out of town.
I would contact the person to find out, if no response after 48 hours, open an unpaid case with eBay so they can reverse the seller fees and record the unpaid items against the buyer.
I've had this happen to me before and received payment after I opened an unpaid item case. Good luck!