It's part of IDW's "remastering process" - when the old comics are scanned in, the text is picked up by the OCR (optical character recognition) software. Sadly, the software misreads certain letters, resulting in the new versions containing typos that weren't originally present. This sort of thing is quite common in IDW reprints, notably in the GI Joe stuff. Examples in the IDW Transformers TPB reprints include "Hissins" instead of Higgins (in the credits of US#1) and "Durasyllium" instead of "Durabyllium" in US#19. Those are just a couple off the top of my head, I'm sure there are more.