I think it is a tell that he has a hand and is thinking about how to play it. BUT, the fact that he is in the hand (ie calls, bets or raises) also tells you he has something. It is just one small piece of information, and continue to use it as the hand progresses, and see the timing on flop, turn and river and compare this to his timing on other hands to see if there is any correlation to how he plays certain types of hands.