(Consider this a preventative measure.)
Evidence: Volume 3 doesn't get quite the rave reviews the previous volumes got (Although there may be some reversal of opinion as well. And apologies for that first link to Savage Critic--do a text search for "Pilgrim." And if Hibbs or Lester are reading this, do something about your archives, guys!)
Evidence: Everyone knows about it now.
Evidence: Objections to seeing it on best of the year-type lists. (He has a point, though--more on this below.)
Evidence: Brian Lee O'Malley gives a somewhat controversial interview. Responses indicate some simmering contempt.
Speculation: I'm not sure if any independent comic in the last five years has approached the hype, popularity, and success of Scott Pilgrim. If you want to read the newest volume within the first month of its release, you have to be early in arriving to your LCS, persistent, or willing to pre-order. It's been optioned for a movie. It's a gateway comic for those unexposed to manga or b&w independent comics.
But is there some resentment for its success? It's certainly a fun little book, but there are clearly so many better comics being published. Shouldn't these more deserving cartoonists get some of the spotlight? Scott Pilgrim and the Infinite Sadness was good, but was by no means the best of 2006.
Also, there seems to be a backlash against the scenester qualities of the book, particularly among younger readers who might dislike the scene which Scott and his friends participate in. (You would think this would be a problem among older readers, but I think Scott Pilgrim actually evokes a sense of nostalgia for many of us.) There are apparently criticisms that the book is too "emo." (Brief aside: does "emo" even mean anything anymore, or are comics people just completely clueless about how to use the term? The idea of an "emo" Supergirl is laughable, but I might be the only one laughing, unless my sarcasm detector is on the fritz.)
Analysis: I really do think there might be a backlash brewing, but hopefully everyone will remember that Scott Pilgrim is a potentially revolutionary comic in its potential to funnel new readers (and I don't just mean converted mainstream readers) into the world of independent/alternative comics. It's not that big of a jump between Scott Pilgrim and the Fantagraphics mainstays of the 90s (especially Love and Rockets and Hate). So when you inevitably hear someone saying that Scott Pilgrim is the only indie comic worth reading, don't take it out on Brian Lee O'Malley--use it as an opportunity to suggest some similar work. And let's not forget that every copy of Scott Pilgrim sold encourages retailers to buy other independent comics as well.