Nonplussed

On the phone to my neighbour she told me that a lady had come to the door to say that this neighbours car warning lights were flashing and a window was down. We live in a secure block and I know everyone so I asked who this lady was. 'Was it Sheena from the first floor? She's quite small and has shoulder length dark hair.'
My neighbour's response, ' I couldn't tell. She had a mask on.'
Well?!