I meant Yagyu Shingan when I wrote Yagyu-hey it was late here....
That said, I'll have to look it up but i am quite sure it was questioned. I think Yagyu Sensei said something like, it wasn't signed, or it looked fishy.
It wasn't Yagyu sensei, but the "issue" you are bringing up is that supposedly the item in question was missing a stamp on it (if I recall correctly). There were any number of legitimate reasons that this could have happened and as Ellis said previously,Yagyu Shingan-ryu itself found nothing partciularly "fishy" about the document itself and found no real reason to question it. I think the tone of the comments on the "missing stamp issue" were originally in more of a "Yeah, this is the real deal. Hmm a stamp is missing, that's kind of odd, but yeah this seems real" nature rather than "Oh man, this stamp is missing. There is obviously something fishy going on here!". I believe Ellis and others have discussed the issue elsewhere in more detail and a bit of searching should pull up the info rather quickly.