Another thing to watch out for is extra knots that have stealthily worked their way into the bridle. This happens to me on the bottom line attachment points (from the kite flapping around when packing up I'm guessing). The short segment that you attach a bottom line to works its way around the bridle and itself, creating an extra knot right on top of the existing knot that creates that short segment, making them hard to find unless you look really closely. I hope that made sense...not looking at a kite right now.
One time I switched from flying full vent to standard, and then my kite wouldn't behave. I couldn't find anything wrong with it on the field and compensated just like you did by adjusting to uneven leaders, so I suspected something was wrong with the bridle. When I got home, I took the frame out of the kite and folded it in half to compare all the bridle lengths (saves taking the bridle off the kite, and works well enough for me). That's how I found the extra knot.