Over the past few days, there has been random error's when accepting gifts as in recent gifts.
the gifts are sent well in advance of the two-week expiration date from FarmVille friends.
people will be in the middle of accepting gifts bouncing back and forth between the game and the notifications area on Facebook and then occasionally receive an error message that says 'This gift data not found.'
This has happened several days in a row and zynga are aware of the issue's and facebook have also been made aware!