If you select an answer for a question, then hide the answer, the question shows up in the list with "0 answers", but italso has the qa-a-selected class applied. In my case, this makes the text green even though there is obviously not an actual selected answer.
Just thought you'd like to know :)
EDIT: also happens after answers are deleted. I'm assuming the selected answer ID is stored in the question row, so either there should be an extra check if the ID is valid, or if that's too complex then remove the ID when the selected answer is hidden/deleted.