A Real Disappointment Makes Me Suspicious

So far this season, I've had pretty easy games.  Generally, I will be assigned 2 or 3 games on a Sunday.  One of them is usually a U-little, short-sided game.  The others are U-11's or 12's.
This weekend, I was sent to a club in the area that is relatively new compared to some of the other clubs.  They have been around for 2 or 3 years.  It seems they are going through growing pains in that the same individuals seem to be more than one team.  Their facilities aren't great. They don't use much in the way of paid trainers and their knowledge of the game is somewhat below average.  We had a U-9 game, a U-11 game and a U-12 game.  I was assigned with two young referees.  One is a high school senior and the other is a college freshman.  The senior is a decent referee.  She needs a little more confidence, but is solid.  The college referee is very good.  He is one of the best ARs I have had.
We worked the games as usual.  Everything went very well.  In fact, the games were completely unremarkable.  The only controversy we had was finding an extra sand bag to put on the back of one of the short-sided goals.  I'm not sure any of the coaches present, on either side, said more than a dozen words to us.  It was a completely routine day of games.  The high school senior worked the U-9 game.  I did the U-11 game and the college freshman centered the U-12 game.
Later that night, I received an email from our assignor.  The coach of the U-12 game send him an email stating we were "horrible" and that we "missed 3 blatant hand balls" and there was "tons of pushing and shoving.  He actually said the club prefers a certain referee and "his crew."  More on that later.  Our assignor was looking for feedback, so I replied with comments similar to the above.
As some of you know, I work hard to try to be a quality referee as do the individuals I worked with this weekend.  We don't always get it right, but we try to do the right things for the players.  I am disturbed by this coach's actions.  It would be one thing if there was some controversial call that occurred with which he disagreed.  However, in this case, there was absolutely nothing to speak of.  I was AR1 in the game.  I didn't sense any disagreement from either team.
 2 weeks ago, I worked games at the same club.  In one of the games, the home side was completely dominating the visitors.  I was AR2 in the game.  During the half time break, AR1 made the comment that he had "encouraged" the home side coach to take a player off the field to make the match more fair.  He seemed proud that he had familiarity with the coach.  I was appalled that he had done this and expressed my concern that this was something he really shouldn't be doing.  It brings into question a referee's neutrality/impartiality.  This particular referee lives in the same town.  Going back to the email to our assignor, the referee mentioned specifically in the complaint as being preferred is also in the same town.  Perhaps I am cynical, but I am starting to wonder if perhaps this club is trying to lobby for "home" referees.  Yes, I recognize this is a tenuous connection, but it seems strange to me that a coach would express a preference for a referee that happens to live in the same town.
I really hope my assignor noticed this point.