Could previous Parvo experience be the cause of my dog's seizures?

Don't be so worried, or concerned, dogs can have seizures just the same as humans, sometimes they can be brought on at random times, and in your case in her sleep. It doesn't sound like something you should be worried about, if their isn't anything wrong with her diet, or the way she acts any other time, don't stress. By the way, my dog shakes in his sleep to, twitches his eye, and rolls his eyes to the back of his head sometimes. This is when he's in REALLY deep sleep, and wakes up just fine with a kiss for me lol. But I think your dog is going to be fine.