I have had a swollen lymph node behind my ear for my entire life. it is not painful and doesn't grow should i tell my doctor?

Yes: Always good to show your doctor when examined so that it can be documented as to characteristics and size in case something changes.

Well...yes..: but I'd hardly go to the ER for this. These are fairly common and do not indicate anything if they've been present and stable. They do not have potential to do anything bad. While cysts and lymph nodes could grow, they follow patterns and if the pattern is not growing, then, it isn't going to now. But, every medical feature should get mentioned sometime.