Google's "unusual traffic" notification

[gall at switch.ch]

A customer reported to us that many of his users have been getting the
"Our systems have detected unusual traffic from your computer network"
message from Google since last week.  Apparently, this is only
happening for IPv6, which makes me suspect that there is some kind of
glitch with Google's technique for detecting what they believe is
automated traffic.

I filled in their form at
<https://support.google.com/websearch/contact/ban>, but I'm not
particualry optimistic that this will help.

The customer is using a /48 from our allocation 2001:620::/32, but so
far we didn't get any reports from other customers.

Any help or insight into the problem would be appreciated.

-- 
Alex

SWITCH NOC
AS559