Hello? McDo? Ano ba talaga?

Few minutes back, I went to McDonald's (Assumption Road) to buy my lunch. I ordered 1 6-pc Chicken McNuggets (Large). Based on the menu board, the item costs Php160. I handed over a Php500 bill. When the cashier punched my order, the cash register's monitor reads Php162. So I asked the cashier "how come it's Php162 when it's Php160 on your menu board?" She stared at the monitor for a while and asked the cashier next to her what could be wrong. They conversed for a while. I couldn't hear what the other cashier said but after their brief conversation, the cashier who took my order shouted "VOID". The manager came and asked what happened and so, the cashier asked the manager the same question I asked her. The manager stared at the monitor and asked the cashier "ano ba ang pinunch mo?" The cashier answered the question and the manager stared at the monitor for a while then turned to look at the menu board and then back at the monitor. After what seemed like forever, the manager said "baka hindi lang na-update yung nasa board." 

And since I was in a rush, I didn't argue anymore but in my mind I was thinking "how come they are not sure whether there was a change in the price of what they are selling?"