Shouldn't be at all related so if your 850's older than a '96 ('93-'95), you can check the codes and reset them yourself, drive it and with luck, the ABS light won't return. If it's newer than '95, then a scan tool will be required to check and reset the codes.
'97 on up 850s often have control unit problems, solved by replacing the control unit but it has nothing to do with a brake job.
Another possibilty, although it'd be rare on a 850, is that perhaps some metal debris is now sticking to a rear brake sensor and if so, cleaning the sensor should work. You'll still need to check and clear the code however.