It sounds like someone might have dragged the fridge or dishwasher or something during the final stages of the building and demo'd your floor. If you allow them to patch it, instead of replacing the entire floor, then get everything in writing. ie: that you can disaprove of the repair within 30 days and they have to stand behind the repair for the same period as the new floor warrantee. If it were me, I wouln't accept a patch. You are buying a new house and you are paying very real money and you want a new, non patched floor to go with it. You need to be happy and it is within your rights to have a new floor, not a used floor. Of course you might also convince the builder that he wants to add that lightpost you wanted, or do something else, extra for you, to make you happy,in exchange for not having to incur the expense of buying a new floor. If I had to guess (I can't see it) I would wager that the blue mark is just on the surface and is some of that temporary mark/print that sometimes appears on vinyl. It can probably be removed with soap and water, if not either have their flooring sub remove it or chuck the whole floor out and start over.