I am noticing an unusual server redirect on certain pages whenever the user agent is Mediapartners-Google/2.1. This is the bot which Google Adwords spiders targeted landing pages for PPC ads.
The redirect can be seen when viewing the server response by using this tool:
Note: you need to change the user agent to Mediapartners-Google/2.1 in order to see the server headers based on that user agent.
I cannot find any software settings that would cause this redirect.
I also can not identify any server rules that would cause this to happen.