I won't mention specific airports, but I was connecting through the UK to the US a few years ago. I departed my origin airport with one large piece of hand luggage, one large piece of hold luggage. We all need to pull out our tablets, phones etc out of our pockets. Anyway in Heathrow, the gentleman in security pulled my hand luggage aside and lifted my laptop out....which I thought I had left at home, had no idea was in my luggage and as such had not separated it as I would normally.
It was scanned without any issues, but my origin airport required laptops to be scanned separately, they never noticed it was in my hand luggage there.