In the letter page of ASM #30, Paul G. Wiener wants to know when Uncle Ben taught Peter that "with great power comes great responsibility". The answer he is given is "The immortal phrase uttered by Uncle Ben... is just one of those untraceable moments in the Spider-Man folklore."
This is just hokum of course. It's not even a retcon so much as it is sloppy thinking, a confusing of "Ultimate Spider-Man" lore with "Marvel Universe Spider-Man" lore.
The truth is that Uncle Ben taught Peter this lesson by being shot dead by a burglar Peter could have stopped but didn't. The utterer of the immortal phrase was Stan "The Man" Lee. Any pretense that Ben actually discussed this with Peter at any time in the past, that he was some sort of prescient Yoda only dilutes the power of the lesson when Peter learns it. So, guys? Cut this nonsense out!