Well, I actually do know she's losing her marbles; at 13 years she's a bit confused sometimes. She used to rely on Cedar, our lab I re-homed, to get her into the house every night. Cedar had an internal "let me in clock." But Pip is capable of barking to come in, she does it all the time.
We were gone all evening to a school program, so we weren't aware of her activities all night. When we got home we were drifting around the house for a half hour before we headed to bed. She didn't bark a word.
I did provide her with a wooden crate stuffed with an old sleeping bag in case she ever got caught outside. She really likes it and because she needs a trim she was probably plenty warm. Maybe she was just sound asleep.
She seems fine. I still feel bad I didn't notice she was outside. Poor dog, she must feel neglected.
Sigh. We all get left outside sometimes.