Like I said in my first post in this topic the seals can be a bit of a problem from time to time with these shocks , you have only been selling them a short time and like you mentioned you have already had some returned because of the seals.
I would just be careful throwing the word “Lifetime” out when selling these, they are not parts store shocks where if you show up with a leaking one five years down the road that they will hand you another one over the counter. The shock owner will have to rebuild them at their cost which I would guess to be around $ 50 per shock minimum with a seal kit and labour. And if you do send in the shock for warranty repair you will find most parts in the shock including the shaft, piston, and even the shock body is considered a wearable items.
Still if you are looking for a high performance shock they are a very good choice.