When honesty calls

This happened last weekend, when I was flying to Austin, TX. My flight was scheduled for 6 in the morning, and I had a late night before. I was woken up by the cab driver who had come to pick me up for (my temporally unreachable by public transport) a drop at the airport. I packed my stuff and got ready in about a couple of minutes and dashed. At the airport, when the security check was going on, the usual question was asked - "Do you have any liquids, sharp objects or food items in the bag?" Quite to my surprise, my reply was probably the most unexpectedly honest (to the point of being inappropriate) - "I don't know." The security personnel and I shared a very odd look for a moment, and then he said, "I guess there aren't any". And he let me through. Reverse psychology?