I couldn't tell you if it was epilepsy or not, the doc would have to determine that, but it is only diagnosed as that if your ds has more than one fit/seizure/convulsion, whatever you prefer to call it. There are various different types of epilepsy which produce different types of seizure. The type of seizure your son had sounds very similar to the ones I had as a child, BUT that does not mean he will go on to develop epilepsy.
You do feel pretty tired and drowsy after having a seizure, takes a few hours to feel on form again, usually, so that is what I imagine the sho menat by taking a couple of hours to come out of a fit. This is called the post dictal phase. Certainly the fit itself shouldn't last more than about 5 mins.
Your mother is probably referring to petit mal epilepsy, which was the old term for the more minor seizures. Petit mal and grand mal. They have been replaced by more specific terminology now, such as absence seizures, partial complex seizures, tonin clonic seizures, etc.
The fits which would come under petit mal, as you and your mum know it, tend to affect only part of the brain, so you can have just an absence, appearing to lose track of yourself, or be daydreaming for a minute or two, or just stare into space,other seizures may cause you to do repetitive stuff, such as lip smacking, blinking.
The major tonic clonic seizures are what most people would automatically think of when asked to visualise someone having a fit, falling to ground, going rigid then having muscular contractions, which jerk the body. These tend to affect the whole brain , which is why you get such a dramatic end result.
Sometimes seizures which affect only part of the brain can suddenly take over the whole brain and cause a major tonic clonic fit as well.
Did your son have any unusual feelings or senations before he fainted? HAd he been unwell, eating properly, overtired? These can all be factors.
I would get him along to the gp and ask to eb referred to have an eeg. Having said that, it will not give you conclusive proof of epilepsy or not, but just gives a recording of the brain waves as they put your ds through various tests. If anything irregular comes up they will be able to check it out further for you. Try not to worry. One fit does not automatically mean epilepsy, and even if it is, life is perfectly liveable with it, even if it takes a while to adjust.
hth