TV-shows sometimes have mid-season breaks (I don't know why, but that seems to be what they do). White Collar seasons 2 and 3 did just that, as you can see on the Wikipdeia Episode list.

I would say that is the most likely cause, and should mean the Intro changed from Episodes 9 to 10 in Season 2, and 10 to 11 in Season 3.

TV-shows sometimes have mid-season breaks (I don't know why, but that seems to be what they do). White Collar seasons 2 and 3 did just that, as you can see on the Wikipedia Episode list.

I would say that is the most likely cause, and should mean the Intro changed from Episodes 9 to 10 in Season 2, and 10 to 11 in Season 3.