OBDII C Codes questions?

[guava]

I had two things happen at the same time. Truck started just fine. I released the parking brake and started to roll. Then I noticed the Parking Brake idiot light was still on and then I saw the check engine light.

Double checking the parking brake showed it was released but the light was still on. I cycled the brake a couple times and the light stayed on. After a couple more stops for errands, the light went out on its own. Parking light still works when brake is on.

Pulling the codes from the odometer, I get:
C Codes
2176
2174
A403
A404
0000

Another time, I get:
C Codes
2179
5700 (?)
A408
AC09
0000

I did pull the codes one other time and got a different variation. After considering this problem over dinner, I went out for a drive and the check engine light has reset itself.

SO....what happened? I've searched for the codes and the OBDII link that Matt400 lists doesn't show any of these codes.