This is one reason why biking everywhere and using public transit is my transportation method of choice - saves me a TON of money. Thus, gas prices have a much lesser effect on me, so from a personal standpoint, I don't feel the effect much. Still, not good that they're going up at least in the short term, for those who have to drive a lot.

I suspect part of it is the holidays and the heavy travel going on this time of year...if I remember correctly, gas prices frequently spike a bit at the very end of the year. It's also partially to do with rising demand for fuel in the so-called emerging economies, which will drive up fuel prices over the long term.
Overall, fuel (and tangentially, food) prices are really volatile and often just go all over the place in the shorter term.