You are almost certainly right that this is a mucocoele (mucous
retention cyst) of a minor salivary gland in the lip.  I've had them
myself.  Assuming this is one gland, it's probably a good idea to have
it removed to prevent recurrence.  Mucocoeles of this type are an
annoyance, not dangerous.
    You should also note any sharp edges on the teeth that close adjacent
to this area, and if present have your dentist smooth them.  Some
patients also have a nervous habit of biting their lip.  You'd know if
this is the case.

Steve