I do it all the time and sometimes I notice and unflag an article. But often not.

I find accidental flags rarer due to the layout versus things I'm trying to tap, however the few times it's happened I only discovered it days or months later when visiting the "flagged" page [0].

Still, there's a kind of guilt, like realizing you unknowingly kicked a puppy who isn't there anymore.

[0] https://news.ycombinator.com/flagged