New 200 Amp Breaker box make noise

I installed a new GE 200A electrical panel and transferred all of my circuits over from the old box. All of them were working fine in the old box. I just needed a bigger box. Anyway, after energizing the main breaker it made a sizzle sound for a second or so and then quit. Kinda freaked me out. I turned it off. I checked to make sure it was seated fully and it appeared to be. I then turned off all circuits and then turned on the main. No noise. I started turning on circuits one at a time. After the fifth or sixth breaker I heard that sound again only it was very faint. so I assumed something was wrong with that particular circuit. I rechecked the connections and tried it again. No noise. So I turned the rest of the circuits on and all was quiet.

I then turned off the main and cleaned up the work area and put the panel cover on. After energizing the main break I heard that noise again. I quickly turned it off and after checking the panel here is what I've discovered:

• The sound comes from the 200 main breaker, not the individual circuit breakers.
• The sound happens randomly and is not circuit dependent. After further testing any of the individual breakers can cause this to happen.
• All hots, neutrals, and grounds as tightened securely and properly connected.

Do you think this is a bad main breaker? The service lines are newly installed by the power company and are locked. Could they possible be loose or not tightened to spec?

What would cause this?