I own a cheap Rival brand rice cooker. Here is a link to the product page. Note that there is an inner removable bowl where the rice is cooked. This bowl is coated in Teflon.
After cooking rice last night, I forgot to turn the cooker off, although it automatically switches to a 'warm' setting after the rice is done. (The two settings can be seen in the product page linked above.) I forgot to unplug the cooker, and it remained on overnight (8-9 hours) in a small, poorly ventilated apartment. Should I be worried at all about possible Teflon fumes? The bowl was only mildly warm when I found it in the morning, and there was no evidence of burning. I was under the impression that Teflon is only dangerous at very high temperatures, but I wanted to be sure.
More generally, suppose I want to start making rice at lunchtime so that I have warm rice ready for me when I come home. Is it safe to leave the cooker on for this period of time?