The retroflex gesture of the tip of the tongue touching the back of the hard palette occurs extensively in Sanskrit. For example in "pandita" (=pundit), the "nd" sound is formed with a retroflex. This is much more pronounced than in any other language I know of because Sanskrit was designed with clear articulation of the various phonomes and their combinations in mind. It can be quite fun to do and very funny to hear. Of course, Sanskrit is a dead and formal language so the opportunity does not arise too frequently.