Post slug does not change – bug?

Hi,

I’ve noticed for a number of my posts when I change the post slug, the guid field in the database does not get updated to reflect this change.

Eg:
1. Create a post titled “Test Post” and save. The slug for this would automatically be generated as “test-post”
2. Edit the post and change the slug to “change-slug”
3. In the front end if you access http://www.siteurl.com/change-slug/ the corresponding post opens properly…however if you pick up the guid from the database using SQL (which I am doing for a particular function) then it still shows the old url “www.siteurl.com/test-post/”

Is this a bug, or am I doing something wrong?