today i replaced my valve cover gaskets after swaping the springs and rockers a week ago. when i went to take the drivers side cover off i notice a white gooey thick substance on the rocker and on the valve cover. it was some kind of build up of some sort. it also smelled alot like gasoline. this was only on the last cylinder's #7 rocker and spring. im not that knowledgable on these things so any help would help. should there be gasoline in that area? and what could have caused the white substance and the gasoline smell?

any info will be appreciated.