selective purge is purging all pages instead of individual page only

Hi there I am testing purging of selective pages in the following scenario.

Page1
Post1
Post2

I check the varnish cache age with curl via e.g:
curl -v http://mysite.net/post1/ | shasum

< Age: 1011
< Via: 1.1 varnish
< Connection: keep-alive

I have noticed when I edit any page or post and then check the post age all pages have a Varnish Age = 0

e.g edit page1 , then all 3 pages now have a age=0

This tends to show me that everything is being purged from cache on any individual edit instead of selectively.

My varnish default.vcl file look like this:

https://gist.github.com/trentster/b7472e67592b929333e4

Any idea why?

http://ww.wp.xz.cn/plugins/varnish-http-purge/