Parsha Trivia and Riddles

Reb Yehuda knows halacha well. Therefore, when he began eating the simanim on Rosh Hashana, he pushed away the apple that was in front of him and asked for a date. “A fruit from Shivas Haminim is kodem!” he explained. But when he was served a piece of date, he shook his head in disapproval and pointed to a date that was in the middle of the table, and said, “According to halacha, I should make a bracha on that one!” said Reb Yehuda. What halacha was Reb Yehuda referring to?