No, this reasoning is correct. This case is quite tricky. It looks at first glance like a version of the gambler's fallacy, since the number of traffic fatalities in one year is presumably independent of the number of fatalities the prior year. But in fact it is not a fallacy; the very fact that this year's fatalities are independent of last year's means that this year's rate is likely to be lower than last year's. It might help to think about the following analogy: Suppose you roll five dice, and you get four sixes (which is an unusually high number of sixes--you can calculate the probability). What is the chance of getting four or more sixes on the next roll? What is the chance of getting fewer than four sixes? Go back and think about how that applies to this case.
Reading without reflecting is like eating without digesting.

Edmund Burke