I disagree 100%. They change all the time depending on what cookies you have stored in your browser. You can prove it very easily by using two different browsers. For example, let’s say you’re using Firefox and you get a price change that looks suspicious like that. Just bring up the same site and search with IE or Chrome, and often you will see the original, cheaper price quoted. You can do the same thing by deleting cookies, but it can be tricky to pick the right ones to remove sometimes.
Travelocity does sneaky stuff all the time, and it seems like it started when they were bought by Expedia. I have clicked to book a hotel room and the room is suddenly not available at that price, and they tell me to search again or offer the room for a slightly (sometimes very) higher price. Just for kicks I will do the same search on a different browser and voila–the room is magically available again at the lower price!