I had a similar experience a few days ago, I crashed the kite a couple of times and generally just had a real unco day (even more than usual

).
Whilst standing on the beach talking to a mate I noticed that my bar was crooked and commented that one of my rear lines must have stretched and that was probably the reason I was kooking it.
My kite only has one knot on the back lines so I knew it wasn't a case of being on the wrong knot so I just went back out anyway.
However when packing up I discovered that the larks head loop had tightened up about 30mm or so above the knot on one side and that was the reason the bar was crooked. (nothing to do with the brand of kite as was suggested....MATE)

It amazed me how much it affected the way the kite flew even when I knew the bar was crooked and was trying to compensate.