Sansui India — sansui 40" led tv some noise comes out after switch off

Address:

Nagpur, Maharashtra, 441110

Hi,
There is always sounds come out when i switch off my sansui 40" led tv... Sounds like some lizard running over the back cover... And it is heard for 10 to 15 seconds... Earlier i had registered a complaint and the engineer told me that, as the tv set is new this type of noise is genuine... Kindly suggest whether is it genuine and there is some fault in the tv set.