Sophos UTM: How do we check Advanced Threat Protection (ATP) case if Source IP address or host is IP address of the Sophos?

Hi all,

I have a problem with Sophos SG 135.

I have two Sophos devices from different places (Office A & Office B). Office A using Sophos SG 230 and office B using Sophos SG 135.

I've already configured VPN Site-to-Site between office A and B.

Recently, I received notification email from Sophos SG 230 at the office A related to "Advanced Threat Protection".

http://www.sophos.com/en-us/threat-center/threat-analyses/viruses-and-spyware/C2~Generic-A.aspx

Especially, Source IP address or host is IP address of the Sophos SG 135 at the office B.

This is log from Sophos SG 230, both have been upgraded firmware version to 9.702-1.

Can anyone tell me what happened? Is Sophos SG 135 at the office B infected with virus?