how to stop using google page speed

Question

I have a wordpress website I'm creating for a client temporarily hosted on http://dev.eatfit.co.nz/

I'm noticing that often (but not every time) that I browse a page (for example the home page), what I assume is the google pagespeed online service seems to rewrite the url's on the fly to optimise things, so I get urls like this coming back to me (viewable in fiddler or in the .html source)

http://dev.eatfit.co.nz/wp-content/themes/eatfit/images/xfoot-logo.png.pagespeed.ic.SWoJqa9Ly9.png

I do not want to happen and I want to turn off the google pagespeed as it is incorrectly optimising the css and also constantly caching so testing updates is painful.

The strange thing is I've never turned on the online google pagespeed for this website and there are no special optimisation plug-ins in my wordpress install doing this. I looked up their online service and apparently you have to put in a special cname dns entry to get pagespeed to work - but no such cname exists on this domain.

It appears that somewhere between the hosting company server and my client computer the urls are being automatically rewritten. How is this happening and how can it be stopped.