kraftsmaid warranty confusion

Hi. I purchased custom kraftsmaid cabinets through lowe's and they were installed recently. My understanding is there's a lifetime warranty on the cabinets.

One thing that confuses is during installation, my installer mentioned some cabinets arrived damaged, so I Had to call kraftsmaid to get replacement parts. They sent those out right away with no questions asked, but also mentioned to make sure that I check all the other cabinets as I only have 90 days from the delivery date to request replacement parts. This confuses me because if there's a lifetime warranty, then how is the 90 days relevant?