We'll know soon enough. This is up on Drudge and talk radio. CBS will have to come out with some sort of explanation and if your analysis is correct they'll have to provide the original document.
Here's how they're trying to spin out of the forgery issue...
Text of memos about Bush suspension (AP claiming white house released forged docs!)
This lag time just gives CBS more "time" to improve the forgery and make it look more realistic!!!