I can't comment on your sister's observations but I did download the pdf file from the provided link and zoomed in on the notary's seal which has an imprinted date of December 12, 2003.
Since the affiant's appearance is dated August 29, 2003 there appears to be something amiss here, too say the least.
After reading your post, I did the same and it appears the December 12 date is an experation date.
That isn't an issue... the notary's commission expires in December 2003. They usually are good for a year or two, so this makes perfect sense. I can't make out the notary's commission number, but there is a site where you can look up the notaries, and there are a number of Patricia Anderson's listed.