[NEEDS SAVES] Upgraded fire-proof objects catching fire a lot

I'm having this problem a lot, across multiple saves. In my current save, I had at least 7 fires in one sim afternoon. 

I tried removing ceiling lights (which have previously caught fire) and using table lamps which were placed on the mantlepiece of the fireplace. There is no furniture within 3 tiles of the fireplace (except for an occupied bassinet two tiles away, which should be invulnerable).

My fire count was as follows:

1. The floor caught fire.
2. The floor caught fire.
3. The cat threw up on the floor while I was feeding the baby, and in the space of time it took to cancel the feeding action, the cat vomit caught fire.
    NB: The vomit was about a tile and a half away from the fireplace.
4. The lamp on the mantelpiece caught fire.

5. The floor caught fire and spread to the couch 2 tiles away.

6. I think possibly the *cat* caught fire? Not sure. The fire started on the tile the cat was on, which was diagonally 2 tiles from the fireplace, and it spread to the tile the bassinet, which didn't burn, but the floor under it did.
7. The floor caught fire.

I can send the save file through, if you like. Shouldn't be hard for the devs to replicate the issue, given that track record.