Artefacts upon playback at 150% view

At 150% view when playing a score, there's trailing thick black line(s) on the stave(s).

Sometimes it's there for the whole line of the page, but its usual behaviour is to sync with where the playback head is playing and increase as it progresses through the score. It disappears when it's the next line.

Hoping someone else can reproduce: Play a score with one instrument at a normal pace (so you can easily notice it) - also at least 30 seconds long I would probably say (it should come on at some point - I believe it's random).

It rather reminds me of this problem.

Using Mac 10.4.11 and 0.9.6.3.