On initial reading of that, my thoughts were
Immediately after Install there would be minimal swelling = good reads
2 days later increased swelling can cause read issues
Plane flight causing edema thus further reducing read range
The rotation can happen, and reasons vary,
How long after install did that happen?
Did you take any prenatals?
Are you <25yo?
Did you tape or corral the xDF2 in place?
Were you “overly” active with your hands within the first 2-4 weeks?
Then the more I read your post, 30 days, that doesn’t sound good.
I think you shipping it back for testing by DangerouThings things is an important step in the diagnosis and if you haven’t contacted DT yet, Amal will likely see your post here and have questions and suggestions for you.
To me, Nothing you mentioned, sounds like it could have been the cause of a failed implant.
I have made many flights and scuba dives, with no adverse reactions, so unlikely it is a pressure-induced issue, this is likely due to the fact the xSeries implants are resin files, and therefore no air voids to act upon; plus Tests we've performed on our x-series tags
It will be unlikely that your new FlexDF2 will rotate due to it’s form factor.