Undercover Boss is a CBS show and falls under the AutoHop category. CNBC is showing reruns of the show and strangely, the autohop function appears to be finding the episodes and tagging them. We know that Autohop isn't restricted to the satellite-provided feeds of the Big 4 channels already because shows that are recorded off of the OTA adapter can "hop". The Hopper must search the full database of recordings and isn't restricted by channel.
I'd guess that the reason only some are tagged is because those may have recently be re-run on CBS.