This represents the f < 5 in the 1830 census. She may have died young, as there is no f over 9 with the Nathaniel Pettit family in the 1840 census. On the other hand, she may have been with Nathaniel's wife and mother-in-law, whereever they were, because the 1850 census suggests they were still alive then.

Fayette Co., KY marriage records list:
Ann Pettit m. Henry Moore 13 Sep 1843 (IGI A458534)