It has literally
I'm sure I've seen it happen on MindControl and Arteezy, probably many other pros.
I'm sure that in the example below, the engine thinks the cursor is on top of the hero portrait when the click command is issued so it's a feature, not a bug. But this probably doesn't take into consideration monitor delay or network delay (Which makes ME think my cursor is not on top of my hero portrait)
I'm sure there could be workaraounds such as:
Don't allow casting a spell on a hero portrait (and the minap, and hero icons on top) if the cursor has been there for less than 0.1 seconds. This I'm sure will solve all of these accidental clicks (Which always happen when you try to quickly move your camera)
Allow users to disable casting specific spells on hero portrait (and the minap, and hero icons on top)