I don't recall him saying that. I DO recall other's, alarmists who have very little grasp of the technology saying something like that. Drexler said that the likelyhood of 'grey goo' is less likely than your car going feral. Imagine your car, one night, breaking out of the garage and crashing fences and eating grass. Imagine your car browing leaves off trees.

NOT gonna happen? Right. Neither will nanobots be likely to do that either.