It wasn't the distance from the bag (which according to the press reports Anderson is STILL arguing) -- it was the intentional act of going after Iguchi with what can only be described as a "cross body block."
Say what you want about CB Bucknor, but he didn't hesitate and stepped up to make a solid call.
There's a picture here:
http://slam.canoe.ca/Slam/Baseball/M...456731-ap.html -- look how far Anderson is from second base.