Thanks everyone!
Yeah it's one of those things that happens once and doesn't happen again for months in between. I am not even sure she was asleep the second time it happened.
kjc, she had a baseline blood panel done when we got her, and usually the vet repeats it before each dental once a year if she thinks it is necessary.
lillymae, I wasn't aware it could be a disc.
I did have the vet check her kneecaps for LP during her last dental because sometimes we hear her legs make a popping noise, and the doc felt that Jenna's knees were in good shape, no sign of disease...but I hadn't thought it might be back trouble. Could this be from carrying her? She is my baby and I like to wrap her in her blanket and take her with me instead of having her follow on the ground and possibly hurt herself jumping up on and down from things to get to me. She tends to slip and slide on our linoleum too, so I try to limit how many times she could take a fall. I am always careful to support her properly. I have three house rabbits and their backs are VERY fragile, so I have some practice in carrying small animals carefully.
I'll speak with my vet again. I'm pretty sure she doesn't have a bad back, she's never shown any sign of pain in it otherwise, but it's not worth dismissing without confirmation. Thanks for the advice.