yup,thats prop twist
like pat said
check limb thickness
take one limb and look at both sides and compare the thickness
i do this with the bow strung
if you have it at bace and set it on the floor you can actuall see right where the twist is starting
then just look at the side and see if they are the same thickness
some times you cant see the differance
then,like pat said,take thumb and forfingers
pinch each side of the limb,and slide up and dowm slowly(both hands at the same time)
any differance in thicknes should be felt
then just lightly take some wood from the strong side of the limb and recheck after excersizing it