My dog Bear did this yesterday. I come home and open up a couple bills in the kitchen and am writing a check when Bear saunters right next to me and opens up the pantry door and is looking around. I'm staring at him and he is clueless that I am watching him. Anyway he is about to grab onto something tasty when I say, "Scuz me" and he gets this, "Oh shit, he caught me look on his face then he quickly scurries away. I'm like WTF? friggin dog either has brass balls or is getting so old he just doesn't give a shit.
I adopted two Welsh Corgi pups many years ago, and had a lengthy time house-training them. It was handy, I'd point at a wet spot or poo on the carpet and ask, "Okay, who did this?" One would always lean forward to look/sniff, and the other would do a Denver....
Mine too (I also have a schnauzer). She pooped in the floor a few weeks back and I just happened to see the evidence. All she heard was me going "what the hell?" and I saw her droop her head down and look back up at me.
It pissed me off at first, but I then remembered her trying to let me know she had to go so I couldn't do anything really. She's very, very good about letting you know when she has to go out. If you're in another room, she'll come get you and give you the stare down.