Sir Alex Ferguson claims the Football Association was "dying" to send him a letter after he was charged with improper conduct.
Ferguson was charged after he came on to the pitch to remonstrate with referee Mike Dean at the end of the 4-3 win against Hull at Old Trafford.
He said: "I have no reaction because I have not read the charge yet.
"I am a bit surprised. But this is the FA. They were probably dying to send me a letter."
Ferguson marched on to the field immediately after the match to remonstrate with the official.
The Scot has been given until 19 November to respond.
Ferguson was thought to be upset that Dean, having already booked Michael Turner, did not send the Hull defender off when he up-ended Michael Carrick in the second half.
United were 4-1 up at the time and, to compound Ferguson's frustration, Dean then awarded Hull a penalty for Rio Ferdinand's challenge on Bernard Mendy.
United's players became increasingly irritated and Wayne Rooney escaped a sending off when heavy challenges on George Boateng and Andy Dawson only resulted in one booking.
Last season Ferguson was involved in three high-profile incidents with referees, two of them after matches against Portsmouth.
At Fratton Park in August the 66-year-old was furious that Steve Bennett sent off Cristiano Ronaldo.
Then, after an FA Cup tie at Old Trafford in March, he labelled Martin Atkinson "a disgrace".
On that occasion an improper conduct charge was not proven.
He did, however, serve a two-match touchline ban and was handed a £5,000 fine for a rant at referee Mark Clattenburg at half-time - a game United went on to lose.
~RS~q~RS~~RS~z~RS~06~RS~)