Wembley's pitch under fire for England games
England boss Roy Hodgson last week questioned the decision to stage an NFL game at Wembley, just six days before his side's Euro 2016 qualifier.
The turf was cut up and scarred after Sunday's game between Dallas Cowboys and Jacksonville Jaguars.
And Maslin said the playing surface was "not as good as it should be".
Maslin said the issue with the pitch had left him "slightly disappointed" but is confident it "will be back to its pristine state after a winter renovation".
"While the pitch will not be of the very highest standard we want for the Slovenia game, it will still be a good playing surface," he said on the Football Association's website.
"We do expect it to be back to its best by March for the Lithuania game.
"Whether it's the England team, which is absolutely at the core of the stadium, or whether it's Rugby World Cup, NFL, Saracens or rugby league, I am very confident we can deliver a fantastic surface for all those event owners."
Speaking before Sunday's contest between the Cowboys and the Jaguars, the third NFL fixture at Wembley in six weeks, Hodgson said: "If I was asked if it was a good thing or not, I would have to say not.
"The pitch, unfortunately, is not in the best of nick anyway, which we're all a bit unhappy with."
Maslin said problems with the "summer renovation" of the pitch was to blame for issues, rather than the run of NFL fixtures.