HBK didn't want to job his Title to Bret Hart at Mania. So he said he was "injured" to Vince aka "lost his smile" to the fans. He then came back like a little while later at Summerslam and everything was fine again with him.
Bret had an idea where HBK would job at Mania when Bret got him in a killer submission and snapped his ankle. Bret wouldn't shake his hand or show any kind of remorse to him. Fans would booo. Shawn would come back and take the Title. Then they would do a tag thing. HBK said it was cool. Then he did the interview about "losing his smile."