Notary stamp is older than Stamp paper date on GPA

sir/madam my cousins land was sold using power of attorney of my mother in 2003 by her uncle.due to old age my mother does not remember about the g p a.the g p a is not non revocable .it is a normal g p a. g p a seems to be suspicions as date of notary is six month old than date of stamp paper used for g p a and few mistakes in the g p a. can i challenge this in the court .please advice me pradyna