Nightmares and night-terrors are actually different things. Nightmares occur in REM sleep and night-terrors occuring during non-REM sleep or between sleep cycles. You don't sleepwalk during the stages of sleep where you dream. It's the night-terrors where you randomly cry, scream, and thrash in your sleep without remembering it. You don't dream during a night-terror, you just go apeshit a little bit.
You only remember the periods of sleep where you dream. That's why dreams seem to jump topic; because they are actually multiple dreams separated by periods of sleep that ate impossible remember. If you were having a good dream but woke up suddenly in a panic, you probably had that dream a while ago and it was during the bout of non-dreaming sleep that something happened to wake you up. It just creates the illusion that you woke up directly from a dream.
Could have been as simple as the ice-maker in your fridge making a noise and startling you awake.