Your experience is not uncommon. A study of Canadian workers' compensation patients with carpal tunnel syndrome reported a long time on the same job before having symptoms. In a group of 964 patients, there was a range of eight to 11 years between start of work and onset of symptoms.

Doctors think it takes this long for the tissue to build up inside the wrist. Once the tissue size gets larger than the space for the nerve, pressure on the median nerve causes pain, numbness, and tingling.

It's likely that a long period of damaging work activity must occur before symptoms start. In fact symptoms may not begin, even when the tissues have changed. It may be another couple years before the worker feels anything. Many workers wait up to two years before reporting their symptoms. By that time even more changes have likely occurred inside the wrist.