"This post was flagged for deletion. Reason: oops wrong button. "

"Oops I didn't mean to flag that" or "oops I didn't mean to approve that"?

I would assume the latter. If you hit the flag button on accident all you need to hit is "Cancel".

That was my thinking. Can't really see a reason for deleting it though.

It's not really "deletion", just a way
to return it to the moderation queue.