goodroi - 5:51 pm on May 7, 2012 (gmt 0)
Sounds like normal personalization of Google serps. You can recreate this without VPN. On the left side of the Google serps you can change your location. Simply changing the city usually delivers some change in the top 10 results. Changing the state or country leads to even bigger changes.
If you want to increase the chances of ranking despite Google favoring sites that are more relevant to the local geographic area you need to boost your SEO.