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At her age it's quite possible she may have had a small stroke, she is quite an old hamster & they can begin to show symptoms like this or have episodes such as this then seem to recover quite well for a while.
If she seems better now then it may not be necessary for her to go to the vet but do keep a close eye on her for signs of anything still being wrong or any other changes.
She may begin to find it harder to get around as she gets older or if anything like this happens again so you may need to make some adjustments to her cage, everything on one level, nothing she might fall off & just keeping food & water within easy reach.