SAM HOUSTON signature on piece of 1838 $5 bill

is Sam Houston's signature on a piece of a 1838 five dollar bill. The issue date is May 1, 1838. T are two interesting stampings on the piece. The first says "FUNDED AND CANCELED. The second says "AUDITED AND CANCELED AUGUST 15, 1845(?). It would seem logical that Texas currency would be collected when it came a state in 1845. This may be a piece of a bill that remained after the bills were burnt. The signature is faint but clear. T is no printing on the back.