One of my friends is an immigration lawyer, so I'll talk to him on Monday and see what he says. I'll post back as soon as I have an answer. Either way, don't get so worried! I do remember reading somewhere on the CIC homepage that there actually is some kind of a grace period for this. I just can't remember where I read it.
ayrazar, do you know have an idea of when the form might have been updated? Was it Nov 30th? I just did a side-by-side comparison of the current and previous version of IMM 0008, and I didn't find any differences. Whatever change they've made must be very minor, possibly even technical to ensure that validation works with the newest version of Adobe Reader which was also released in November.