I noticed that when I use Find in the session or when editing a function, in Direction=Up mode, it sometimes matches incorrectly.
I have reported this to support, and they have logged it as a new bug. So if you run into this, it's not necessary to knock yourself out trying to isolate and report it.
You may be able to experience this bug if you edit a large function, use Ctrl+End to move to bottom, Ctrl+F, Find What=d, Case=Match, Direction=Up, Search Type=APL, Search Scope=to End, Find Next. Keep doing Find Next. It sometimes finds incorrect d's at the end of a line, such as the d at the end of ":end".