I think the OP means that the item arrived on a particular day, but the eBay record (either in purchase history or sold items, depending on whether they are the buyer or the seller) shows a different date.
We notice that sometimes, whether it's because they're on US time, or for some other reason only they know.
No big problem unless it causes a postage defect due to the order arriving on the last date of their estimates.
It also sometimes happens with the payment date.
