AITAH for ghosting a client for work we completed but a product that was possibly faulty.

I own a relatively large (small business) that offers anything construction and we are very good at what we do. We redid an amazing his & hers bathroom for this client and the work turned out amazing. However, after we completed the shower I guess some of the grout turned darker as if it was wet and never returned to the natural grey it was.

After inspecting the shower, the water drains properly and there’s no leaks anywhere. We make a great deal of water proofing and inspecting everything before we tile for this exact reason. The grout is a huge deal to this client bc it’s only in one part of the floor. After speaking with the client it’s clear that he expects me to pay out of pocket to fix this when my job is to provide and install a good working shower I can not control faults in material or whatever work was done before myself.

I have a feeling the type of drain installed by the plumber under the tile bed was not the proper drain (again that’s not my job). So AITAH for avoiding this guy right now bc his expectations are in my opinion a little out of line.

I’ve attached pictures of the spot he’s talking about and the full job just for fun on my profile