my instrument cluster is really bright when my car first starts up..(M)
 

then it fads a little after about 1 min, its still lite up so i can clearly see it, but not as bright? did this always happen and i just never noticed it?

Mine cycles between bright and medium every once in awhile.
 

Haven't paid much attention, though, since I have no dead lines that don't light up. So long as the whole display is lit, I have ignored this.

Is the amount of light cast on the light sensor changing
 

while this is happening? (look at your instrument cluster carefully, and you'll spot a little round opening for a light sensor)

I'll look at that. the middle display is fine its the needle and the gauges that dimm