They look like hot pixels not getting properly removed by your darks, combined with movement between frames.
I had a similar issue with hot pixels sneaking through in Astro Pixel processor when I was using a drizzle process and you could clearly see my dithering pattern in them, little square spirals instead of a line of dots in my case.
Any sensor will have some hot pixels, which is not to say that they will be visibly "hot" in an unstretched image. it does not mean that the pixel will be at max value (though some might be) just that they will not be as linear as most. If you have a handful of pixels which accumulate dark current 10% faster than the average of the sensor then they will likely show up when you stretch the data, even if they were not visible before stretching