Leaf spring sag??

So over the course of time my Tacoma started to lean or sag to the left side. Then I noticed the back left seems to sag more than the rest of the truck. Obviously I have a 4 inch lift sitting on 2.5 inch blocks on the rear. Seems like the driver side leaf spring is sagging a little lower towards the front of the spring compared to the right side. Haven’t noticed anything abnormal or any cracks. Any idea or is it common over time with lift kits??

 

Trucks only 3+ years old........ "Over time" ??? Naw man.........ain't that. That trucks practically new.

 

That was my thoughts too. I’ve been wanting to buy a set but I’m worried I’ll have to replace my shocks. Rough country told me I can’t add new leaf springs but I know that’s a lie.