Yes, it is very suspicious. But the only thing is- clearing your browser history will sometimes help your browser run quicker/better. Flimsy excuse... but still a valid one.
I was just thinking of that. If he cleared out browser history on a regular basis, then it's not as powerful (the clearing part, not the look up part). Of course if it's like BC where he only deleted specific files pertaining to this particular search, he's in trouble.