py3status: mpris - problem with mousewheel on_click for volume (hardcoded playback toggle?)

I have this in my config;

mpris {
  format = "[[[{artist} - ]{title}]|[{title}]]{previous}{play}{next}"
  on_click 5 = "exec amixer set Master 3%+"
  on_click 4 = "exec amixer set Master 3%-"
}

But every time I mousewheel up or down to change volume, the playback also stops and starts.

Previously I had setup an on_click 1 to toggle mpc/mpd playback, but with that, clicking the area started and quickly stopped, so I guess there is a hardcoded playback toggle in the module already?

Ninja edit: though thinking about it, there must be a difference between the mousewheel issue and my previous left mouse button toggle issue - if there is a hardcoded toggle on any mouse button, then in the mousewheel case, the volume should change and the playback should toggle only once (on to off), not twice like it is (quickly off then on again) as if there were three events (volume change, off and on).