Just bought an RX65. Worked great on the way up to Minnesota. On the way home it started saying "SelfCal" then the scan mode I was in would blink. It did this on serveral different occasions. Then one time after doing that it said "service required." I turned it off and on again and it went through the same process ending with "service required." I then unplugged it and put it on the floor of the car because I was mad that it broke. Later I plugged it back in and it worked fine the rest of the way home. I talked to the guy I bought it from and he said that heat can cause that to happen sometimes. Is this true? Should I be concerned about this or just wait to see if it happens again? I only plan on using the RD on trips and not in the city so I haven't used it since. Thanks for any info!