Yes, Ive seen them do that. And, how many times on the same cast do you feel multiple small bites and never hook the fish? When that happens I chalk it up to "must have been a small one" or "damn thing doesnt want to eat it". Then again, how many times on the same cast do you get multiple small hits with no hookup, then BAM fish on! What is going on? Does the fish just nibble out of curiosity a few times, decides its good, then eats it? Who knows.

Many of the really solid bites I get I dont hookup on. Thats why I theorize they are small fish actually biting the bait and shaking it (yeah, Ive seen small ones doing this). And, many times Im staring up at some cool bird and barely realize I may have been bit, set the hook, and yeehawwww its a nice one. And sure, Ive had real hard bites from nice fish.

Who knows. One thing I do know is Im setting the hook regardless of what the bite feels like, and asking questions later:P