You could dispute whether your statement was a fallacious argument or not, but it was indeed an ad hominem attack.
I would note that it was a pointless argument, since it is unlikely any of the same individuals were involved (if the CDC was involved at all), and one issue of this nature does not point to 'a history of poor reasoning'. It just points to the fact that science is never finished.
BTW, the 'current advice' on second-hand smoke dates to at least 1986. There's been quite a bit of time for someone to find issue with the conclusions; I'm not aware of that happening in any legitimate context.