My '08 T4R began doin this as soon as it got hot this year, too. Sometimes randomly while driving down the road (thought there was a short in the steering wheel controls or something), sometimes when I start after a hot soak. With as many people as it seems to be happening to you'd think...
I'd like to upgrade my /08 SR5 (JBL Synthesis, 6 disc, no NAV) to Bluetooth. Does Toyota have a kit? I've seen lots of posts about the AVIC, Kenwood, etc. but the Synthesis really kicks it up high, and let's face it, the Garmin transmission through FM really sucks!