It's not very likely that you'll experience a seizure just because you worry about
it. There are Psychogenic Seizures, these are Psychological in origin. Psychogenic Seizures are not going to produce Grand Mal symptoms. www.forbes.com/sites/alicegwalton/2012/04/16/can-stress-cause-seizures-news-on-conversion-disorder/www.aafp.org/afp/2005/0901/p849.html
It might be helpful to understand that not all seizures are Grand Mal, in fact most aren't, I had seizures for 15+ years before they were diagnosed. So I was working, driving cars, etc. during my seizures. This, of course, is not recommended until after they're controlled by medication, but I didn't know I was having seizures, though I had multiple times sought out help. My seizures were profound feelings of Deja Vu followed by memory disruptions. The whole thing would last less than 20 minutes, and I would be fine afterwards.
If you believe that all seizures are Grand Mal, it would be natural to be fearful of that, but to realize that many are temporary alterations in consciousness, consistent with many seizures that occur, is not nearly so scary.
Lastly, migraines can produce effects similar to seizures, for a dramatic example, see the following link. This reporter suffered a migraine, which briefly altered her consciousness and she ended up speaking babble. She appeared on T.V. shows afterwards, quite normally, explaining what happened. Again, altered consciousness, no Grand Mal. m.youtube.com/watch?v=ssiLkxTTrzc
You should discuss your concerns with your doctor, he/she may be able to help ease your fears.