I once had an agent hold up the line because my document wallet was in my hand and I didn't stuff it back into my backpack quick enough. She said that was a third item. Who knows what they've been through before we get to the gate. It could be she had been reprimanded that day for not policing better.

ETA - since then I carry on a nylon reusable shopping bag that fits the personal items dimensions and throw my purse along with all my bits and bobs into that, like my document wallet, snacks, headphones, etc.