Some state verbs can be used in the continuous form

• with the adverbs forever, always and constantly to show annoyance about a repeated habit,
• to make requests and questions more polite and less direct,
• to emphasise a strong feeling at the moment of speaking, and
• in some idioms and set phrases.

http://www.bbc.co.uk/learningenglish/english/course/towards-advanced/unit-5/session-1