If you already were claiming itemized deductions on Schedule A, instead of claiming the standard deduction, then this should not be an issue. The full amount of gambling winnings income could be cancelled out by the miscellaneous deduction for gambling losses. If you did not itemize your deductions, then you may only get a partial or even no benefit from the gambling losses deduction, depending on how far below the standard deduction amount amount you were before the gambling losses deduction was added.
Even with just the $1000 in additional gambling income to claim, you should still amend the return. Before you do so, make sure there are no other pieces of unreported income that will pop up.