Plane.pseudoDistance(vector) returning strange results

this is my plane:

constant -455.99966

normal:0,0,-1



the distance to the point 92.42078,408.01218,-452.03912 is, according to the method pseudoDistance, 903.0388.

i'm no math genius, but this seems to be a bit wrong. the correct result is -3,96054. where's the bug? who can fix it?