It could be this known problem with the Spektrum 10X module:

http://www.spektrumrc.com/Articles/A...ArticleID=1693

Attention Spektrum module owners, When using the Spektrum JR module in JR10X transmitters, under specific conditions it’s possible that unintended servo outputs can occur.

All of the following conditions are necessary to produce this issue:
JR10X transmitter (all other JR 10 channel radios are immune)
Spektrum AR9000 or JR921 receivers (all other RXs are immune)
At least one non-digital servo is attached to the receiver.
The programmed travel adjust/ sub trim or P mix must drive at least one of the servos past its end point.
If all of the above conditions are met it’s possible that an un-commanded servo out can occur.
Spektrum engineers have solved the issue through a modules programming change. All future Spektrum modules shipped from Horizon will have the new programming installed. If you have experienced this issue or are concerned about this programming you may send your module in and we will reprogram it at no charge.
If you have any questions or concerns please contact our Product Support Team at 1-877-504-0233 or [email protected] We are available 8am to 7pm, Monday through Friday, CST.
For module reprogramming please fill out the attached form and ship your module to:

Spektrum Service Horizon Service Center 4105 Fieldstone Road Champaign, IL 61822