Okay, so I've been seeing more and more of these audio dropout errors, and I'm not sure if it's an issue with the wireless Sennheisers (G2 kit), the Sound Devices MixPre, the tapestock I'm using (Maxell miniDV ME), or the XH-A1 itself.
I make sure that batteries in the wireless packs are always fully charged when in use. I usually switch them after three hours of use, or when the battery meter gets to 2 bars, whichever comes first. Same thing for the MixPre, changing batteries after about 3 hours. I use over-ear headphones to monitor all sound through the MixPre, and never heard any of these errors.
If anyone has any ideas on what it might be, please let me know.
Here's the actual video clip with one of these errors. You'll notice it dropout twice as Jill says "fully integrated", and the slight bit of audio you hear is from channel 2, Mike's mic:
Here's the waveform in Soundtrack Pro, notice the lack of signal on channel 1: