I had this experience too in a xy graph with the right axis legend longer than 2 characters (a value of 100.0 is enough for this to happen). Once the legend has moved to the right of the Y axis I found no way to move it to the original position, even reducing the size of the graph plot area or the lenght of the y scale.
I had to use a simple lable instead of the scale label in order to display it correctly. BTW this permitted me put the lable over the Y scale and with special attributes (i.e. size and color), which I cannot obtain with the axis label.
Anyone has some consideration on this?
Roberto