Can't figure out this bug!

[naturalgirl]

Yesterday I repotted one of my phals because I suspected the media was breaking down (it was still in the original sphag from when I bought it) and it turned out it was a bit. When I was poking around I found that some of the old moss between my 'chid's roots was black and there were silver flecks in it that almost looked like bits of aluminium foil. On closer inspection of these flecks I saw a BUG crawl out of the black moss and poke back in deeper. I dug after it to try and see what it was but I couldn't figure it out. It was sort of beetle-like bit a bit more elongated, and moved pretty quicky, and it's body was kind of segmented, a bit like an ant. Pretty sure I saw little antennas.
I only found the one, even when I picked through the old moss to search for more. I also looked over the plant itself and didn't see any others, so I gave it a good blast of water to knock off anything that might be hanging on.
I know this isn't a case of: mealybugs, scale, aphids, any kind of worm or caterpillar, thrips (MUCH bigger than thrips), nothing that can fly at all.. so what IS it? Could it just be a generic beetley thing that found it's way in there?
I'll be checking this orchid regularly, but so far it hasn't shown any sign of pest damage and it lived in that sphag for about two months in my care (since it was in bloom when I got it).
Any ideas as to what this might be? Or what those silver bits in the old moss were?