I'm not familiar with the 850, but in general I've never heard of a clutch
noise going away unless it was replaced by something worse.

If they admitted they didn't resurface the flywheel it's likely they didn't
replace the pilot bearing in the flywheel, either, and that is usually what
makes noise when the clutch is engaged and out of gear. The pilot bearing
doesn't come off like the rest of the clutch when the pressure plate is
unfastened and is easily forgotten. Or the new one could be bad and the
dealer is hoping against the odds that it will magically become good.

If the noise were on an old clutch, I'd recommend you ignore it until the
clutch had to be done anyway since pilot bearings rarely seize - they can
make that noise for many years. But a new clutch shouldn't do that. Put your
complaint in writing and lean hard on the dealer when you still have the
noise next week. That is below professional standards for a clutch job -
heck, its below my amateur standards.

Mike