This is no big deal, I just wanted to point it out while I was thinking about it. It happens to me on Mac and Windows.
When you start plexamp the art work from the first song you play is always the same artwork that comes up on all notifications from that point forward. Example below.
Keep up the good work I love Plex Plexamp is going to be great.
I know there are bigger fish to fry. Have fun with it.