something is either sitting on your headers (a wire or vacuum hose) or oil is dripping on them. it's pretty common when the valve cover starts leaking because the oil will drip out onto the headers, burn, and not leave a trace other than a smell.
rub a cloth around your valve cover to check for leaks
you should be good to drive if you can verify your valve cover is the problem and your oil level is fine. valve cover leaks are slow and not threatening over short periods of time
Last edited by peytonracer4; 08-14-2012 at 01:56 AM.