I think this guy's onto something.
How long does the laminate go unused and are you running a dehumidifier?
I always leave enough of a leading edge on my prints to wrap the roll once, partially to protect them and partially out of habit, when we used the arlon gloss 3420, right where the paper and liner met would form a glue line that would always end up in my prints, so I started leaving a foot or so on the end. I don't really notice that effect because I'm looking at the print, but now that Mcclay mentions it, I have noticed that webbing pattern on the takeup reel.