Sportster 5 Tuning Problems

I've had a Sirius Sportster 5 for several months and it just started jumping channels this weekend. By that I mean that the radio will periodically change channels on it's own. Usually the change is 1 channel down from current, but sometimes it's 1 channel up. However, the change is always 1 channel and appears to occur at completely random intervals. During a 1 hour period yesterday morning, the problem occurred 7 times. During a 1 hour period yesterday evening, the problem occurred 3 times.

Has anyone else experienced or even heard of this problem?

Thanks for reading.

-George