Yea, that's fairy common.
Think of it this way. Your CNS is not much different than the electronics in something like your TV or computer. Now imagine a lightning strike at your home and you didn't have any surge protectors. As you can expect, everything gets fried. That's in essence what you did - you fried your internal electrical system.
Now to take that one step further, there are basically two schools of thought on this being good or bad for you. I happen to be in the camp that says that you need to fry your CNS on a semi-regular basis - maybe every other month or 10 weeks. I believe that it is that shock to the system that helps your CNS deal with the added loads you are putting on it. Sort of like scaring the shit out of the guy that is dating your daughter when he least expects it - it keeps him on his toes around you, and hopefully isn't so "touchy-feely" with your little girl.
Like the other day, I was asking the young lad that is sniffing around here what he thought would hurt worse, getting punched in the eye buy a guy "of equivalent size to me" or getting shot with a .44 magnum. But I digress....
The other side says that you don't need such dramatic one time shocks and that milder ones more frequently are better.
There are good arguments for both sides. I just know what works for me.
B-