Radio shuts down by itself

Hello, Im new to the site and have a problem with my wife's 08. While listening to the JBL audio system, it shuts off by itself while listening to satellite radio through the AUX port. The problem just started a week ago and could be resolved by just turning the radio back on. Sometimes it will come back on in the AUX mode and sometimes to FM. This last time though, the AUX/CD button did not work but the radio was fine. I figured something was fried so I left it off. After about 5 minutes, I turned it back on and everything was fine. Anyone encountered this problem? Can't take it to the dealer since it isn't currently broke. Car still under warranty. Any ideas?