Freaky MS box

Been running this box 4 years, I think. No probs. Ran around last night, wacked on it pretty good as usual. Typical drive home from the cruise.

Decided today to run my valves since I haven't adjusted them since January on the dyno.
Anyhow, I'm resting my arm on my MSD box and noticed a little "burning" while touching the engine. So I grabbed my 12V tester and SURPRISE!

Is this a normal thing? Works great. I bet it's been like this since new.

I just thought it was odd that my box is 12v hot all the time. Had wifey light it up while I snapped a pic. That aint my dainty hand....box.jpg