You hadn't said anything about your postoperative visits to the surgeon. What did he said to you about success of the operation? Are there any exercises you should do? Did you wear protective collar or something similar? What he said about going back at work?
Because, as I know, leg pain isn't connected to the ACDF. It sounds like a problem with lower spine.
Did you said to your surgeon anything about it? And when did it started?
I recommend that you tell surgeon about leg pain and maybe a need for some radiology studies of your lower spine.
I hope that you'll soon be well. Cheers!