I know that if you call the credit card company after any card purchase, they can verify the purchse that qucik...some good ones will call you to verify a large purchase on your card. A While back, dad bought a new fridge, and you know how expensive those can get. Well, the company called us to make sure that we actually made and authorized the purchase at the store.
Maybe the delayy you are talktin about has something to do with how long it takes for it to get printed on paper or from the card companies' computers to an online-style activity checker.