I received the following from Len Wein, who co-created Wolverine and wrote the comic book he mentions below…and who, more importantly, owes me many lunches and his undying gratitude for my friendship. Len writes…
FYI, the Wolverine image on the stamp is from the splash page to Giant-Size X-Men #1. It's both penciled and inked by Dave, though the version on the stamp is probably from a bad stat. You can check out any of the 42 million reprints of said issue for verification if you'd like.
BTW, I own the original art from this page. Trust me, the original looks better.
Who cares? It's only a UNITED STATES POSTAGE STAMP. Why should they bother getting a clear image on it? For that matter, why should they not print their expensive hardcover reprints from eighth-generation stats? Really, I don't know why consumers (and the artists themselves) aren't more outraged at the bad reproduction we often get when anything is reprinted.
In the meantime, several folks have identified the source of the Iron Man portrait stamp. It's from Avengers West Coast #50, pencilled by John Byrne and inked by Mike Machlan. So I think we've now identified all of the art sources and there's one more name that should be mentioned.
I've also heard from people who've written to the website address of the United States Postal Service about this and have gotten back a form response. It tells them that if they believe a correction is necessary to a stamp, they should write (paper-style) to a certain address. That's fine but I think the burden of correcting these errors should lie with the Marvel people. You can't expect the U.S.P.S. to know the difference between John Buscema and Gene Colan but someone at Marvel should. There's some individual at that company who's in charge of working out the details of this arrangement with the postal people and that person needs to put things right.