There was an incident last
There was an incident last week with Modern Family setting CGMS-A flag. Normally, this is never supposed to happen and was some sort of fluke caused by ABC. I happened to be recording this program and noticed that WMC was a bit buggy after the recording happened. Specifically, I noted that the first 9 minutes of Modern Family was flagged with CGMS-A flag (0x01) and WMC treated it as Copy Never.
Fortunately, part of the WMC bug appears to be that it doesn’t delete or restrict this content even though it is flagged and “expired” after 90 minutes from recording. Several recordings after Modern Family were also noted as you describe in their first minute of recording on other channels. This seems to be some strange artifact resulting from WMC seeing the CGMS-A flagged content. I recommend that you reboot and see if this behavior goes away as it did in my case.