The visitors pulled off a shock win at Arsenal on Saturday but struggled to match that performance as Gedo and Ahmed Elmohamady secured a hat-trick of home wins in eight days.
It was Blackburn's first loss in seven games and Appleton said: "After the euphoria of Saturday there was always a danger of the players being unable to pick themselves up and repeat the type of performance they showed.
"You've got to give credit to Hull. They started the game okay and they certainly came out of the blocks second half really well."
The one silver lining for Rovers was goalkeeper Jake Kean, who followed up his Cup heroics against Arsenal with two more impressive saves to deny David Meyler and Jack Hobbs.
Kean's form is keeping former England international Paul Robinson on the sidelines and Appleton added: "He's obviously a lad who's had an opportunity and his reputation is growing game by game.
"He's got half a chance, the kid. At the start of the season, he was probably third-choice goalkeeper and he's taken the mantle on and he's earned the right to be number-one keeper at the minute."