Hello jbeale,
Yes, there seems to be a minor interruption in communications between the server and the station, resulting in the gap you highlighted.
As of now, the data doesn’t get filled back. However, future Shake OS updates will have this feature, so no gaps will appear anymore in such cases.
Your last message is also correct: all data that the Shake records can be found at this address: /opt/data/archive/ and then (also for all readers) YEAR/NETWORK/STATION/CHANNEL/<DAILY MINISEED FILES>.
As, sometimes, browsers block ftp requests as the ones coming from rs.local/, we have prepared a page with alternative data download methods: How to download your data.
Also, if you deem it necessary, you could consider a Cloud Backup, as another Shaker has set up: Cloud Backup - #12 by wmvanstone.