I've been monitoring the approval ratings since he got elected, and, since the 1st couple of months, his average approval rating (Silver's or RCP's) has been between 38-43%. The odd thing is that they go up or down a little, but they mostly don't appear to have a correlation to events in recent news cycles. He's up near 43% now, and it's not like the events over the last few weeks have been overly helpful to him. People keep saying that his response to Cville was the lowest point of his presidency, however the polls in the few weeks after 8/12 had him going up a point or so. I'm the kind of person who likes to have logical explanations for things, but I will accept your random variation as the only apparent answer.