If you use a special tool included on Google Analytics, located on Behavior - Experiments, a malicious user could launch SQL Injections, or other web attack, on remote websites using Google as a proxy.
Enter your website in the form (example: http://www.yourwebsite.com/index.php?id=1' OR 1=1--)
Check out your access log:
188.8.131.52 - - [06/Nov/2013:13:23:47 +0000] "GET /index.php?id=1'%20OR%201=1-- HTTP/1.1" 404 - "http://www.google.com/search" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.4 (KHTML, like Gecko; Google Web Preview) Chrome/22.0.1229 Safari/537.4"If you resolve the IP address you will see google-proxy-66-249-93-25.google.com.
I believe this is not directly a Google security issue. Just keep your website secure and no trouble will come in your direction.