You are the first person I've seen with this problem. Are you on pc or console?
I'm playing on the XBox 360 with the latest patch but this has been happening since I aquired the shout which would have been by the 2nd patch.
It's not hugely gamebreaking, but when you manually save sometimes the game defaults your Shout to "SPRINT".
This is only really as inconvenient as where you happen to be when you next use the Shout.
I am sure other people have been affected by this.
Ages ago there was a thread "Ridiculous Deaths In Skyrim" or something along those lines and there were other people who'd accidentally Shouted themselves off a cliff with the Sprint. I'm sure some of those guys were facing an issue similar to my own.
Since the latest patch I'm playing more so I shall try to remember to take a log of how often this is happening.
Az
EDIT - Also I suppose I am more aware this is happening because I often use "Become Ethereal" to speed up the process of getting down a mountainside, since when you 'become ethereal' you can't fall to your death.
So I keep my Shout as "Become Ethereal" by default so when instead of 'becoming ethereal' your character sprints 15 feet into mid air... and then faills to their death and you've got to reload the last save... it stands out in your head more.