Uh, no, I don't think so. At least, I've never heard that. And if they ever said it (it would have to have been in the 90s, when comics were insane and I wasn't reading), they don't say it any more. Yes, but he immediately went into the X-Men, where he's been for 40 years, and where they quickly turned him into a mutant. Hell, Fox has even been able to claim Quicksilver, who was created in the X-Men and was a villain there for about 15 minutes before he joined the Avengers and has been there for the past 50 years. Interestingly, though, he will also be in the next Avengers movie. Apparently, his 15 minutes as an X-Men villain in 1964 was enough that Marvel can't stop Fox from using him, but his 50 years as an X-Man are enough that Fox can't stop Marvel from using him. Marvel isn't even allowed to use the word "mutant" in their movies and TV shows, although I'm not sure if that's a contractual stipulation or an editorial edict.