o2 sensor expected behavior?

Is it reasonable for an o2 sensor to go out after a clutch replacement? I know that they're not related, but after driving a mile or two after leaving the garage, the check engine light lit up. I proceeded to head back to the garage to have them check the code, and after some testing, we found out that one of the o2 sensors wasn't reacting. Ideas?

Thanks,
-steve
1999 4runner sr5
160k manual

Did they plug it in? Did they damage the wiring? Sounds like something was either bumped, broken, or not hooked up correctly after the transmission was re-installed.

Thanks Kris.
They took the hit on it and replaced the part for me. It must have been something the mechanic did when putting it back together.

Good deal.