Upson was linked with a move away from the club in the January transfer window.
Craig Bellamy and Julien Faubert left the club in the transfer window.
“The person who has the biggest headache in the transfer window is undoubtedly the manager,” Upson told the Evening Standard.
“He may have to make a decision on a player who wants to leave but he doesn’t want to let go. As far as I am concerned there was never, ever a genuine enquiry. There were quite a few rumours but as far as I am aware, that’s all they were.
“I have to say the club have done a fantastic job in what could have been a difficult month.
“They’ve done the right thing and maintained their ambition on the pitch, which is something I was concerned about back in December.
“The one player who’s gone was out of their control really. It was a situation where the player (Bellamy) took things into his own hands.”