John, it is an outlet type GFCI, and after reset another 5 minute delay occurs. Nothing else on the line except the lights. I did find out however that there was thunderstorm/lightning occuring just prior the this problem surfacing (I was out of town). Maybe these dimmers are fried, but still the delay sounds like something is heating up and then causing the problem. Carl, I know i have a problem and don't doubt that the GFCI is doing its job. I changed it because i wanted to eliminate the possibility of it being bad. I have had a couple of them go bad before, so i know it is possible. It is quick, easy and cheap to replace one, and if that is not the problem and you find yourself with a spare, no big deal.
Thank you both for your replies.