It seems the Delta "lifetime" warranty seems to really be until they stop selling that product. I have a shower set where the finish has gone bad. They say there is a newer style that will work and that they will sell me but since they no longer make the exact one, tough luck. After a few Emails the tack moved to "you must not have done the required maintenance" which was not true. They in went to "do you have your original reciept". Then with nothing else to say it pivoted to "prove this was a manufactiring defect".
Just be aware "lifetime" seems to be 10-15 years or whenever they change the style. Be sure you save enough tile to be able to go in and change the valve body. When I do it will not be Delta.