Sorry for the lack of progress on this but my mother in law had to be relocated to a new and better assisted living facility and I had a mishap with the trailer that slowed things down here. More on the trailer mishap later.
So I heard back from the manufacturer. After I sent them several pictures and experiments I performed on the product it has been determined (by me) and confirmed by the manufacturer that the grit is actually unground pigment pellets that escaped their grinding and filtering process. While investigating what the grit might be I took a small fine file to the Monstaliner that was left on the edge of the can and found that the grit turned to powder with very little effort with the file. The owner believes that there is a hole in the screen that filters the ground pigment pellets. So the pellets showed up in my finished surface.
The solution is to lightly sand the surface which will remove the surface pellets, re-tape the edges of the trailer and apply another coat of Monstaliner. The manufacturer sent me an additional gallon and installation kit free of charge.
Hope to get this done later this week as we have furniture to move from the mother in laws old place.
Regarding my trailer mishap. I live in an association out in the woods and the local road maintenance contractor was brush hogging the shoulder of the road across from my home. He got into a windrow of road gravel and stone and chucked a good size piece of limestone into the side of my trailer. The trailer was in front of my garage about 60 feet from where he was working. It hit the trailer in the back panel. My trailer is screwless and epoxied to the frame so in in order to replace the panel, all the panels, lights and trim from the nose cone back had to be removed and replaced. Needless to say I was really

but the associations insurance company covered the repairs and now I have a half new trailer. I had to drive 5 hours each way to the factory but at least its fixed and I have it back in my possession now. While it was at the factory I had them install a cover for the ramp door spring and an upper aluminum cabinet in the nose.
I'll post up pics when I apply the third coat of Monstaliner.
PS I towed the trailer down state 3 times in the last few months (about 1500 miles total) and a trip out to Gettysburg (about 1700 miles round trip) and the floor has held up very well. No cracks, splits or staining. I had some oil from a tractor leak on it and it wipes right up.