That could be a software glitch with the Ipod not recognizing the button when in use.
Here is a clause on Motorolas website about it:
This device supports Bluetooth Advanced Audio Delivery, Audio Video Remote Control, Hands-free, and Headset profiles. In order for Bluetooth devices to communicate with one another, they must utilize the same Bluetooth profile. To determine the profiles supported by other Motorola devices, visit www.hellomoto.com/bluetooth
. For other devices, contact their respective manufacturer.
Certain Bluetooth features including those listed may not be supported by all compatible Bluetooth-enabled devices, and/or the functionality of such features may be limited in certain devices, or by certain wireless carriers. Contact your wireless carrier about feature availability and functionality.
More details are listed on this link:
Does your Ipod have the TEN Technologe NaviPlay Bluetooth Stereo adaptor?