I know it's gone now, but the easiest way to find out if it was grit would be to collect some of the tirchs [or grit IF it is grit weed] and just apply a bit of friction and pressure and if they stick together your smoking good weed, if not you've got grit.

I must admit though, it doesnt look like any of the grit weed i've seen, if anything i'd say sugar but you know what your smoking - i mean, it could just be the light for all we know.