So the intent is for pregenerated structures to catch on fire?

Yes. Fire spreads farther in the 1.8 snapshots. I don't think it was expected that villages would burn themselves down, though.

This is rather out of hand. I don't mind fire spread speed by difficulty, but I do mind if things that didn't catch on fire do catch on fire. I think that this A) may have been a change of fire distance per difficulty, which would be annoying, or else is a actual bug. I think this clearly is a bug because pregenerated villages (op's blacksmith was a natural village one, which may have been confused for something he built) can catch on fire, and even if this was a intentional change, things that shouldn't catch on fire will.

Reopened.
Didn't realize that "my blacksmith house" a pregenerated village was meant.

Can also confirm this is happening. Sometimes it looks like lava has "leaked" onto the grass beside the blacksmith. Other times when there is no lava leak, I assume it has been caused by flames from the blacksmith's lava well.

If you come across it quickly enough you can temporarily put it out, and fill up the lava well if you want to, but mostly you turn up to find large chunks of villages burning down.