So, the dog was on the side and the legs were moving as though he was running?
It is possible. That is one type of seizure that my dog has had.
It's hard to say without seeing it though. A vet should do blood work to verify that nothing is wrong. But for the most part, there won't be anything that the vet will be able to do, unless the dog continues to have seizures within 6 week intervals. The blood work is just a precautionary in case something else may be wrong.