The 33-year-old goalkeeper made his first start for the club in the final-day draw with Hull City.
Van Gaal was speaking to the club’s official website after witnessing the Spanish goalkeeper keep a clean sheet on his first league start for the club in place of David de Gea, who was forced off towards the end of last weekend’s clash with Arsenal with a hamstring complaint.
Having replaced his compatriot against the Gunners, the former Barcelona star would go on to deputise at the KC Stadium and gave a good account of himself, producing two fine saves to deny both Ahmed Elmohamady and Nikica Jelavic.
He was fortunate to see Paul McShane’s tap in from his spill ruled offside in the first-half but, having showcased his shot-stopping prowess, there was more than enough for Van Gaal to be pleased about.
Asked whether he was surprised to see Valdes show such great reflexes after being out of first-team action for so long, the Dutchman said with a smile: “No, he is very quick and explosive. He is very good on the line, so this game was created for him!
“But in the first-half he let one ball loose and it was a goal, so he was lucky that it was ruled offside.”
Van Gaal might need to call on Valdes on a more regular basis in the future, with De Gea’s future at Old Trafford still unclear ahead of the summer transfer window.
The Spain international, who has just over 12 months left on his contract, has been linked with a move to Real Madrid since the start of the season [h/t Marca] and his manager has now urged him to speak out over the rumours.
"I cannot say [when it will be resolved],” Van Gaal told the BBC on De Gea’s future. “He has to say something not I."