i did my valve cover gaskets and oil change and spark plug/new radiator and noticed the check engine light on car was sitting for 7 months ...it cranks well runs good i drove it for 30 minutes the transmission isnt slipping nothings wrong it feels better after i changed plugs and oil i used ngk no leaks at all from my valve covers everything feels good could it be a false code or is it something wrong i dropped a small load of tranny fluid while changing rad btw

 

Plug in an OBD2 scanner and see what code it's throwing.