I read it in a travel article on how to get the best deal on airline flights some time back but if you google something like "do airlines track your internet search" you can find plenty of articles that support this business tactic/model. Really it only makes sense for them to do so.
You can also swap up like do a search with Firefox then IE then Chrome but once you have used all 3 for a single search start deleting cookies and temp files.
IMHO