No, any notary can notarize a will--there are "special" notary publics. Maybe what they meant is that under the Texas probate code (Section 59), there is some specific language (a specific form of an affidavit) which should be used by the notary when notarizing, but that would be easy for anyone with the internet to look up. It just be that they don't want to do this--some banks and brokerages only want to notarize materials related to their customers' accounts--and could not come up with a better excuse.