Those are nice bites, it just feels like the lure has touched down on the bottom sooner than it should have. It does depoend a bit on how you work the lure whether you get them or not though, the bigger the jig and drop, the more likely you are to get them. If you work the lure less and don't do much lifting and dropping, you're more likely to get other types of bites.
I guess the equivalent when 'dead sticking' (or just giving the lure an occasional twitch) is when it just goes 'light' - there's no rap or donk, you just lose the weight of the lure as a zander picks it up and moves slightly up in the water with it. Those are exciting too
A lot of the zander bites can be very subtle, it can take a while to get your eye in woth them, as Steve says. It's worth striking hard at absolutely anything. It takes a lot of effort and concentration to do it properly all day long.
And those who were seen dancing were thought to be insane by those who could not hear the music