Is it possible the recording device is "re-clocking" the signal as it comes in?
I know high-end audio guys always talk about "re-clocking" - - is there such a thing?
yes, there is such a thing as "re-clocking" and that could be what is going on in both of the examples above.
with the Tascam HD-P2 (for example), there are menu options to specify the audio source (mic in, line in, or S/PDIF), and you also need to specify the clock source (internal, S/PDIF, or Word Clock)... to continue this example, if you send the HD-P2 a S/PDIF signal, but have the clock source set to internal, it'll re-clock the incoming data based on it's internal clock. so, if using the HD-P2 to sync up with another A/D, it's important to choose the WC option for the clock source.
in both examples above, the actual gear used wasn't specified, so it's hard to know exactly why their was drift between the sources. if the two recordings were using the same clock, that wouldn't have happened, so my suspicion is that some of the recording gear was re-clocking the signal...