Could headaches after brain surgery really be cause from scar tissue causing small seizures?

Yes: Yes. Post-operative scar tissue can become an irritative source in the brain leading to seizures and headaches. The only way to determine if this has happened is to obtain an eeg. This painless study can determine if you are having seizures which may be the cause of the headaches. It would also be helpful to have an MRI study to evaluate the surgical site. A copy of the old MRI is helpful.

Probably not: Although constant headaches have been reported after craniotomy surgery ("post craniotomy headaches), i think it is too much of a speculation regarding the small "seizures.". Consult a neurologist.