Adword Ads Referer URLs

Why would i be two different referer urls for an adwords click?

[NovaPhoenix]

Hi,
A bit of a cross-topic issue this, but as its specifically about google adwords, i thought this would be the best place to post.

As i am trying to monitor keyword usage from google as well as the actual adword itself, i have a script that takes the keywords from the referer url and while 95% of the time this works a treat, the other 5% or so show the referer as an actual url string.

Ive tracked the cause of this as being a redirection script that google uses for adsense ads so instead of the referer url being 'google.com?q=keywords', the referer is shown as 'google.com/url?q=mywebsiteurl', which totally messes with the keyword tracking.

Has anyone else noticed this behaviour with adwords? and does anyone know why this referer behaviour only happens with small percentage of click-throughs?

[Yidaki]

>Has anyone else noticed this behaviour with adwords

<edited because i was wrong>
<edited again, damn>

The string

url?q=

comes from Google's tracking urls from the regular serp's. They sometimes do tracking tests.