Catapult dog - what is this?

[im_nomad]

I have two questions for the board today, so I figured it'd be best to keep them separate, as this one isn't really behavioral I don't think.

Molly has developed a weird sleep thing that she's had a fairly long while but is increasing lately. She is an older dog, 14.5, and during the night she does move around a bit more, getting off her pillow, walking around a bit, and then returning. I chalk this up to her getting older.

The odd thing that is concerning, and to be honest, startles the hell out of me, is when she's sleeping (mostly during the day) and will suddenly jump off her pillow like something bit or pinched her. Most times she just looks a little confused and walks around a bit, and returns to lay down, but there are times when she practically catapults off her pillow, goes all out, wipes out in the middle of the floor (I have laminate so she loses her footing when she does this) and really looks startled. She doesn't yelp or do anything like that, and doesn't appear to have been in pain. She doesn't limp or anything after.

Her bedding is washed regularly and she's always had flea meds etc. She was even dewormed three months back as a general precaution (I was starting chemo and the vet recommended this as part of a general check-up to keep her healthy as possible, not because she had worms per se)

Has anyone else ever seen this with a dog?