I found that rebinding is a frequent occurence and any time you make a major change to settings that you need to rebind and IF you do not follow the correct sequence the bind will NOT always take effect.
Actually Zim was the one that brought that to my attention about 9 mo ago when I had a suspected gyro setting problem. Turned out that if your making subtrim adjustments on the rudder you should rebind as the radios are not consistent on actually transmitting the changes you made. DX6i radio is querky at times on this and sometimes just disconnecting the rx battery and turning off the tx and turning back on the tx will solve that problem. I have went from a >+12 to a <- 6 with NO change in the subtrim on the heli itself and but once the tx was turned off then back on or rebound it was evident that a change had been made.
Just my personal findings while playing with the radio on a bench seup.