I would say you nearly started a batter fire.
A scary phenomenon of spontaneous combustion, that not many people I know have heard of, unless that happen to work in a chippy.
Fried scraps will spontaneously combust. I have personally seen this occur, but am not sure of the exact process. Guessing I would say that as the bits dry out air and thus oxygen gets to a finely divided surface (bubbles of batter) and it ignites, possibly due to the batter or surroundings retaining heat.
I was taught to always pour a bucket of water in to the outside waste bins of chip shop cooked batter waste to prevent this occurring.
An example reported a couple of years ago apparently in a batter bin inside the chippy
'Batter bin' caused fire at chip shop, says owner
As reported in DevonLive Chip Shop owner Lee Grayling saying:
... fire started in what is known as a batter bin, where excess pieces of fish batter are discarded. ...
... "I have heard of this happening in other chip shops - apparently the batter can generate heat. ...
Another reference: By Thornhill Insurance
Fire Prevention in Fast Food Establishments
Bits or Scraps (depending on where you are from!) can be a huge risk to Fish and Chip Shops and Fast Food Establishments and are often overlooked. We personally have seen numerous instances where the waste was left in the shop after closing time and these have spontaneously combusted, leaving the whole shop ravaged.
Waste should always be stored as far away from your property [sic] ideally in a metal bin and this is usually another insurance warranty.