That is a crazy tiny flat. I may have only caught one that tiny before. On the Missouri River once caught one about that size on a big ass wad of crawlers. Didnt even have a clue there was a fish on til I saw it dangling sadly from my rather large hook.
I was suprised too i had seen a small twitch in my line so decided to reel it up. Didnt feel anything, and noticed my other pole moving around. Dropped the first pole and reeled in a rather pathetic channel. Finished reeling in the first pole to recast and there the little guy was. Got it on a redworm.