I was purchasing a vanity today and the salesman mentioned something no one else has before.

My vanity is only going to be 18"deep because of my narrow bathroom. I was planning on doing a granite/quartz top wit's an under mount sink. He mentioned that I might not be able to use a sink mounted faucet because of the backsplash. I told him I wasn't going to have one (not granite one, but most likely tile on the wall as a backsplash) and he said okay and that when I went to look for countertop, I needed to have the faucet picked out ahead of time to make sure it would fit.

I was planning on getting a widespread faucet, but am worried it won't work with the narrow vanity. Am I worrying over nothing or do I need to be concerned about the faucet?