Speedo light on start up immediately goes out?

[rufcar]

I only have my car about 2 months now and I have repaired everything that was not correct or that bother me. I notice that on start up in my garage the speedo light come on for a few seconds and goes out. Once I drive out of the garage into day light it goes back on! Shouldn't it be on all the time when the engine is running?
I also notice that now that I re-grounded both frame sensors the dash lights are a bit brighter and no longer blink!