Vcore fluctuations are a function of your PSU and motherboard voltage regulators (from what I understand). The more mainstream the PSU and motherboard are, the more likley and the more your vcore will fluctuate. I had this problem on my P4C Northwood based rig which ran off a P4C800 deluxe mobo and a Antec PSU. However, on my sig rig which runs off of a FSP Group Epsilon PSU and a DFI LP board, the vcore doesn't move... ever, and I mean ever.
As the previous poster said, .03 is not a big deal. If I remember the ATX specs right (search THG for PSU stress test) the fluctation tolerance for vcore is +/- 5%. So on your vcore you are fluctuating a mere 2%, don't sweat it.