I started sleepwalking as a teenager and it continued for years. I had many episodes similar to what you've described. Somewhere in the middle of sleepwalking I'd come partially awake. I'd be in a state of semi-wakefulness and semi-dream and I really couldn't distinguish dream from reality until I awoke fully. I looked fully awake and I would remember the episode the next day, but my brain was dreaming.

It happened when I was over-tired and was caused by REM sleep getting out of whack. I was aware enough to know if other people were in the house and where they were. I'd do things like run to them shouting, "Call the police, there's a dead body rotting under my bed!"

My husband would reassure me I was okay, tell me I was sleepwalking again and I needed to go back to bed. But if I was home alone I'd feel terribly confused, trying to figure out what was happening. Even though I was partly awake, the dream state was intensely realistic.

As Fresia said, if it continues it would be a good idea to talk to your doctor about it. But a one-off episode can happen to anyone if you're overly tired or stressed out or on medication.