ik it's not the thickness bc i've been playing around with that today.... my laminator doesn't really have temperature adjustment minus the 3mil vs 5mil settings. I think maybe it isn't spending enough time under the rollers?

Yeah it seems like the seal didn't get it as well. I am pretty sure you can send things through twice, though, but I'd double check your laminator just to be sure. (The ones I've used, I've definitely sent through twice sometimes)