1script - 10:08 pm on Nov 27, 2012 (gmt 0)
Thanks, goodroi. I agree with you on not obsessing about rankings, and I personally don't spend much time looking at actual positions. It's just this case where the upward movement of some KWs contradicted the overall trend, which piqued my interest and made me go look at the past stats.
I actually do collect ranking stats whenever they are reported by Google, automatically, but never have much time to look at them (except in this case) because, like you said, with all the personalization, localization, day parting, traffic throttling and the rest of the results joggling that's going on, nothing ever makes much sense.
I'm combing my site with a fine comb to find any technical issues right now. Nothing has turned up yet but it's a large site - never know what you might dig out.