Then why don't I create a ad that says: "Pre-notice of amazing sale! Order tomorrow and receive 95% off your purchase!" and then change it at 11:59PM so that it's no longer valid. My example is extreme, but shouldn't they have considered that before they posted an offer with only two qualifying statements?!
Edit: I'm certainly not a legal professional, so my opinion is not the law. On most print advertisements, I see advertisers give a disclaimer such as "We are not required to offer any mistakes in printing etc." This covers them legally since they need to advertise honestly.