mp20 Red light

[JDigital]

So I have had an mp20 running on a cube tank for about 2-3weeks... no problems, silent, aligned right (as quiet as I can make it), anyways, sitting here tonight enjoying the freshly sanded tank... I turned the mp20 off, added the sand, and then when I was done fired up the mp20 and turned it down to it's lowest... 10secs after turning it on, I get a blinking red light, pump shuts down for 5-10, then turns back on for 5-10 secs.. the back to red blink...

I can't see it being an overheat issue, as it barely feels like its been running not warm at all (compared to others I have felt).. its aligned properly.. I've unplugged it for now, and just tried again, and same thing...

I can't see/hear any sand in the wet side...

What could be the reason for it doing this... It was brand new (still is).