Just got a 3800+X2, vcore is fluctuating, is this normal??

yes, thats normal, the voltage does fluctuate a little due to inherent variation of input mains power, the way the PSU regulates it and the way the motherboard serves it up to the cpu.
Also the sensors used to monitor said voltage also fluctuate a little.

As a general rule (very general), expect to se a +/- 0.01 to 0.05v fluctuation in ones core voltage from whatever is standard.
if it varies by more than 0.05v under steady cpu load, or changes by more than 0.05v when going from full load to idle you may have a problem, either poor input power, a bad psu, or poor motherboard voltage regulation.

same with cpu mhz measurements... depending on method of measurement it can vary by quite a few Mhz.

i wouldnt worry