"Unusual traffic from your computer network" notification

Not worried but curious: at the first Google search today I had this message: "Unusual traffic from your computer network" notification ; my system is clean, so I wonder - I already read https://support.google.com/websearch/answer/86640?hl=en why I had this message.

 

Are you positive your system is clean? About the only time you will get this message in error from Google would be if you are using a public proxy and it is detecting other connections on the IP.

Check with something simple like the Network graphic in Killswitch. Reboot and start Killswitch. If that graphic is lighting up heavy you have an issue. I don't know what security you use, but I've found the firewalls of most AM suites are very, very poor at monitoring suspicious outbound activity.

 

Scan your PC with at least:

1. Malwarebytes Anti-Malware
2. Hitman Pro
3. Kaspersky Rescue Disk 10.

 

Well, I use a multilayer defense, HIPS, FW, - AV - naturally - and sandboxed surfing, and regularly I scan and check my system. Moreover, three days ago I restored a disk image that never caused Google alerts, today was the first and the only one. Emsisoft antimalware says to me: clean, and the same PowerToolIV 4.3, XueTr and NoVirusThank in all their modules. Also HijackThis log is clean.

 

Kaspersky Rescue Disk 10: negative
Killswitch: negative
Comodo Cleaning Essential: negative

 

Got exactly the same 1 hour ago.
I think it's maybe a Google problem....Or actually some IP "confusion" generated by the VPN, since lately I have got some strange behaviors when connected through it.

Update: confirmed. Issue due to VPN. When not connecting though it, no problem at all.
Also I changed my VPN server and the problem did not occur again.

 

Yup, it is a Google thing. I got that when using a certain Proxy. A precaution from a spamming network, botnet or DDOS attacks...