Chihuahua had a seizure.

Hi , my daughter's dog is very tiny weighing just 3.8 lbs. Last night he was on my bed and accidently rolled off, he was making a wimpering noise and when I saw him it was like he was having a seizure his legs were rigit and his whole body was stiff , this lasted for about 2 minutes then he came to. He was a little quiet after that but within 10 minutes he was completely back to normal. My daughter told me that this happened to him when he was four months old he wiggled out of someones arms and fell on the floor with exact same symptoms. She had called the animal hospital and they said he probally knocked himself out and to keep an eye on him for concussion symptoms which he did not have. He does have an appointment to get neutered in two weeks. My question is why does he have these seizure type episodes when he falls down? do you think it is very serious? He seems absolutely normal after both falls he eats drinks plays . Just very worried about him he is just so tiny and I feel its not even safe to put him on a couch or bed. can a hit to his head cause these symptoms should I take him to the vet imediatly or wait till he goesin two weeks? These episodes have only happened with both falls. Thanks

Thank you Dr. Marie that makes me feel a lot better but we will mention again to the vet when he goes in for neutering thanks again, Jennie