Mine settled about .5-1" after a month or so - but they started out at 3" lift. Are you carrying alot of weight in the back? Assuming you got the regular-duty springs (since you called them 2" lift); they are very soft and will sag with much weight. For instance, the reason I say they settled .5"-1" is because it depends on whether I measure with or without my little 10" sub+box and tools. Before I put all that stuff in I was at 2.5" lift, now the 70lbs or so of stuff I have in the back dropped it about .5".
Anyway, all that to say: How much are you carrying in the back?
How much lift did you get out of the front? Perhaps you have the 931's instead of the 930's? My front springs only settled a minute amount while the back settled noticably.
EDIT: btw - they are a really good leaf and they don't sag as easily or quickly as other leafs, but they will eventually sag. After a year of HARD use, mine have only lost a tiny amount since the initial settling. All springs will "settle" at first.