I have a small lump behind my right ear bit down to my neck its painless and moveable is this a seriouse matter ?

Probably benign: This is a common area for epidermal inclusion cysts to form. These are benign cysts that can form in the skin. Other considerations include lipoma which is a benign fatty tumor, or an enlarged lymph node. If the lump persists, or you develop any other symptoms with it, see your doctor for further evaluation.

Not likely: It could be an old lymph node even from childhood. If it does not change in size, has no other associated symptoms, not usually much to worry about.