There are 3 reasons in the code that deals with money or property that is received post filing and gambling winnings are not one of them.
http://www4.law.cornell.edu/uscode/html/uscode11/usc_sec_11_00000541----000-.html
(5) Any interest in property that would have been property of the estate if such interest had been an interest of the debtor on the date of the filing of the petition, and that the debtor acquires or becomes entitled to acquire within 180 days after such date—
(A) by bequest, devise, or inheritance;
(B) as a result of a property settlement agreement with the debtor’s spouse, or of an interlocutory or final divorce decree; or
(C) as a beneficiary of a life insurance policy or of a death benefit plan.
