Is it normal to have a few power surges when truck is first started on cold mornings? I'm not totally familiar with grid heaters on cummins and just figured that was what was going on. All lights on he truck will dim down and go back to normal for the first 5-10 minutes while running.
Any help would be great.

 

Yep, sounds like the preheater cycling is exactly what you are experiencing. The ECM will cycle one grid at a time, below a certain temperature, until your road speed gets over like 15 MPH. Each grid draws over 100 amps, which causes a significant voltage drop on the rest of the electrical system. Totally normal.