My new puppy had a seizure!

We just got our new Great Dane puppy yesterday. He turns 12 weeks next week and tonight he had a seizure! It was so scary. Foamed at the mouth and deficated involuntarily. Afterwards he got up and ran around like a normal puppy. We just moved so we don’t have a vet yet so we just called a random emergency number at a local veterinarian. She told us that he probably has low blood sugar and to give him some Karo Corn Syrup. He seems fine since but I just don’t know if this is a one time thing? If we should just give him corn syrup regularly to prevent this? Will he grow out of it? I’m just so confused at this point. Both his parents ate AKC registered and we did not pay a backyard breeder price for this pup. Anyone had advice or insight on this?