Opus Quad - Screen Waveform Lagging - Glitching

Just got an opus quad open box.  Regret buying open box, store insisted well tested.  Unit plays fine, however have noticed the waveform will randomly appear to glitch, lag, jump.  RX3 always played waveforms smooth.  Also notice it will take long time to load tracks or playlist from USB, again randomly.  Most of time things load very smooth, and the waveform plays smooth.  But not always.  Unit is running latest firmware.

Is this normal?  Suggestions?  Should I return for new?