It very well could be. Chronic low back pain has been linked with poor balance, especially when the eyes are closed. Delayed muscle response has also been reported with chronic back pain. Good balance requires quick reaction time on the part of muscles and the ability to regain an upright posture.
Active rehab seems to improve these functions. You may need to revisit your physical therapist now that you are back on the job. Specific training to restore these skills is possible. The rehab program can be designed to match your required tasks on the job.