Shaking after surgery (day 3)

Hellos, I had a microdiscectomy done on Tuesday Dec 17 and ever since during recovery I've been experiencing shivering whenever the oxycodone and tylenol start to wear off. Is this normal or is it concerning? I will say there was more jelly than my surgeon anticipated and the hard disc was petruding out the other side of the spine (jelly on left, disc on right) so I had to be under anesthesia for an extra hour because of that.