Variation in Core Temps?

One of my i7 920 cores is a good bit hotter than all my other cores. #2 core runs hotter than the rest

idle temps:
Core 0 = 41
Core 1 = 38
Core 2 = 47
Core 3 = 40

The difference between the coolest core and hottest core is 9'C

Is this normal (if the 3rd core), did I get unlucky with the batch, or is there some other reason?

thxs

That's nothing, I have seen a 23c difference at idle.
Core 1: 23c
Core 2: 46c

That however is a stuck sensor.

My guess is that the IHS and heatsink are not flat. If you don't like your warranty you could try lapping them.