I pulled into the last open spot at the grocery store, only to see a woman in a red car mouth 'I was waiting for that' from the lane. I'd already started turning in, so I parked. She circled and took a spot way at the back. Felt like a jerk, but also... was I? The unwritten rules of parking lot conduct are a real minefield. Has anyone else had to make a quick call like that and felt weird about it after?