Is the device rooted?
Did you make backups of the GA seed somehow or somewhere, and if so, where were those stored?
Will
Here it is straight from my T-Mobile personal account although I had to black out my name and number:
My cell is not rooted and I did not have any backups. I've heard of the rooting process and what it can do but I personally never had a need for it.
so you were using SMS based GA or running the GA app on your phone?
Will
GA app.
a) that funds can only be withdrawn from your account when the yubikey is used.
b) that their logs show a 3-sec (long-press) was actually performed on this withdrawal.
I will ask them right away on these specific points.