Keyboard note doubling

When I play on OP-1 keyboard sometimes it plays two notes instead one. As if I typed on a regular keyboard and itt woulld look liike thiss. It happens with all big keys, not with particular one.

Is it normal behaviour? I think the problem is in bad rubber caps/nipples inside buttons. But I don't know if it's problem of every OP's or just mine.

I had that problem on jus a few keys.
It cleared up after a while.
Wasn’t sure if it was dust from the factory, but it coincided with the seq and user 8 keys triggering them selves occasionally.