It is a sign that it is not properly sealed. If water can penetrate then it needs better sealing.

That’s what I thought. Every speck of oil makes an immediate stain so I already talked to the stone guys and said I thought it was not sealed enough and they blew me off. I’ll try again.

It’s so easy to seal it yourself. Requires no skill so you don't have to wait on your fabricator to do it. Just buy sealant at Home Depot - the “511 Impregnator Penetrating Sealer”. Get the 16 oz size which is the smallest. That small bottle will still outlast you in the home. Do NOT get the one that says ”enhancer”.

You wipe it on thinly. Wipe off any excess and any drips down the backsplash. Keep the windows open, or if the weather is too cold, run the hood exhaust.

Having said all that, marble is a porous stone. You can prevent the water stains your OP mentioned. The oil stains you later mentioned may be a little tougher to prevent. That is the nature of marble. In Europe they have marble in kitchens and bathrooms that are decades old and are etched and stained and nobody cares. You can’t alter the intrinsic makeup of marble, but the sealer will help prevent most stains.

That is the sealer they say they used. I don’t understand why it is allowing the water to soak in and giving zero seconds to clean up a dot of mayo or oil before staining. Installation was in August. Is there not a better one?

Tenax Proseal. Several coats please.

I second Joseph's recommendation.

OK, spoke to the fabricator and I was wrong. Tenax Proseal is what they used. They say that it is totally normal for steam from boiling water to do that and it is not a sign of anything amiss. Anyone agree/disagree? Thanks for your help. I have no idea.

You need more coats of sealer. I bet they only used one coat.

It gets wet and then it dries. I don't think that's actually a problem.

But more sealer should help.