Subject: cool sensation in-closed for sometime jar immediately after opening-why

There's a glass jar sealed for a few hours in a cabinet(not in a 
fridge). It has cookies in it. When I open the jar and put my hand in 
immediately, there's a cool sensation perceived on my palm. After a 
few seconds the sensation is felt no more. WHY do I feel the 
sensation?????
  This phenomenon intrigues me. Can you help me out????
By the way even my friend feels the sensation, so there's nothing 
wrong with me.(or my friend).

Re: cool sensation in-closed for sometime jar immediately after opening-why