Although the comments themselves were innocuous, including a statement that he believed Webb to be the "best man for the job", they contravened FA Rule E3.
Manchester United manager Ferguson has until 4pm on May 16 to respond.
Ferguson had said: "We are getting the best referee, there is no doubt about that.
"But (getting a bad decision) is definitely our big fear.
"We have the players to do it all right. We just hope it's our turn for a little bit of luck."
The problem for Ferguson is they were delivered last Friday, two days prior to the game.
That contravenes the rule which now states no manager should speak about a referee in advance of the match being played.
As the United boss just served a five-match touchline ban following comments made about Martin Atkinson in the wake of his side's Premier League defeat to Chelsea at Stamford Bridge on March 1, there is some concern at Old Trafford about the likely punishment.
However, in this instance, it does appear unlikely a suspension will be imposed.