I use CO2s so no pump to make noise. I'll have to check the cables next time its doing it and see if that will help.

I do have the the low spacer. It seems that there is just a bit of slop over the hub so that it can rock back and forth. It's not an issue with not having the cassette tightened enough but more the cassette is too big for the hub? Here's my attempt to explain how it moves.