Pullock,
Yes you're right, smoke from hot brakes is regular occurrence and as has been noted in this thread, a couple of oil drops or a bit of dust can add to the mix. Sorry - was just adding my (sadly, seemingly ever increasing... ) weight to the 'well-done, better-safe-than-sorry' camp. Not suggesting an evac every time a bit of steam comes off the discs.
Cheers
TD67