It's a trap!

The ‘guest right’ is an ancient and sacred tradition dating back to the First Men. Any guest who eats his host’s food, customarily bread and salt in particular, is protected from harm for the length of his or her stay. A guest who does not highly trust his host will immediately ask for food upon arriving at the keep. Ill fortune is said to fall upon those who betray this pact, and it is an offence punishable by the gods themselves.

I have a gift for you as well. Your life.

My children… you’ve disgraced the Lannister name for far too long.