Yes, It is normal. The voltage will go down after the circuit breaker kicks in, this is the grid heater turning on heating the air entering your engine. Then click/clunk the voltage will then start going up. It is the draw from the grid heater and the charging of the battery. The grid heater controls smoke/ emissions at start-up.
'07 SLT MegaCab,2WD,Auto.,3.73 LS,5.9L,Line-X Liner,Built 9-06, Detroit TrueTrac, Fluidampr, TransGo shift kit, Smarty Jr., Dipricol Boost, Trans and Pyro,NRA Life Member