My last GSD was 6.5 years old when she had her first seizure. Since she developed them at a later age I suspected it was something else going on with her.
I would definitely see your vet and I would also keep a log on her seizures so that you can track of the frequencies. Did she have any vaccinations recently?
Good luck, I know that seizures can be very scary for both you and your dog.
Bear GSD 10/16/11
Elsa GSD 12/23/03 - 11/10/11