Have a min pin.. my does the same thing, she also likes to do a spin action for no apparent reason! My min pin likes to share the recliner in the evening, or when ever anyone is sitting in a chair she likes to sretch out at your side.
Would reitterate earlier poster, train just as you would any other dog, it is really easy to fall into the mindset that they are so small hat you give him special privileges.
My 110lb male Black Lab knows the 9lb Min Pin is his boss!!