3 inches of squat isn't the issue. The issue is; does the suspension feel like it can handle the weight by not excessively swaying.
Consider this;
Empty, your suspension is topped out. So sway comes from suspension compression only. But when suspension is preloaded with 3 inches of squat, you now can sway with the additional action of suspension movement both compression and extension. Adding air bags, overloads and/or a sway bar helps to stiffen up the suspension to help reduce sway.
So, does your truck sway more in turns? Does it bounce more on bumps? If so and it's affecting safety performance, you may want to stiffen up the suspension regardless of the overall squat.