Had that, really sucks, especially in the morning. Like everybody said stretching is key. I would put the ball of my foot on the front door sill and drop my heel, gives a very good stretch and helped a lot. Lots of good info on the net for how to deal.
In your helmet, no one can hear you scream.
V-Strom 650 Adventure "Maxwell"
DR-Z400s "Little Donkey2"
xt250 "Little Donkey" - sold August 2013
Honda Rebel "The Wee Beastie" - sold May 2013