Sorry to hear about the weakness.
I went through the same thing with microdiskectomy. Extreme weakness in one leg. I was unprepared for it. The sugeon was such I jerk that I never got any answers at all about it.
In a way, my situation was worse because I think the doctor tried to cover up the damaged nerve by causing me to bleed internally. They he blamed the pain I had as a result of it on my activity level. (though my activity level was close to comatose after the surgery.
But in any case, I'm 3 months from my surgery and my leg is getting stronger, with the help of good physical therapy. It's taking a lot of work on my part. The P.T. is really training me to do the right exercizes to strengthen all of my muscles, back, legs, stomach, shoulders, the works.
If you get good physical therapy for sure you should get stronger. My primary doctor wound up in a wheelchair after his back surgery and today he walks with a limp, but he's walking! So keep up your hope.
By the way, I have been told by several people that the sooner you start physical therapy the better. Keeps scar tissue to a minimum. Don't be afraid of P.T., the first few exercises are done in bed with minimal movement.
It will take time. You will get stronger. As for the weakness being normal? I don't call it normal. But obviously this happens some times.
If you are not comfortable with the explanations your surgeon gives you, get another one, but don't tell the second one who did the surgery, otherwise you'll just get second hand treatment, a different doctor, but the same treatment, just as you would have if you stay with the original doctor. These guys stick together! If the first has anything to hide, then the second doctor will help the first hide it.
Good luck, Ricebird