Originally Posted by ctsketch
Whedon said Ultron is the movie he wanted to do from the beginning but had to do an origin movie first
Still, there's no evidence he ever told anybody other than maybe Feige and the head honchos about his plans for Ultron. In any event, there's nothing to suggest that he consulted with Pearce and Black about it to tell them to foreshadow/easter-egg Ultron in IM3.
Happy's remarks are just a joke, and coincidental at best. Or serendipitous.