ZeroAccess rootkit found by ShadowServer

I got an email from the campus administrator that ShadowServer found ZeroAccess rootkit on my laptop.
This is the message: (i've cut out the ip addresses)

"timestamp","ip","port","asn","geo","region","city","hostname","type","infection","url","agent","cc","cc_port","cc_asn","cc_geo","cc_dns","count","proxy","application","p0f_genre","p0f_detail"
> "2013-09-15
> 20:00:09","(IP)",52001,1103,"NL","(city)","(city)",,"udp",
> "ZeroAccess",,,"(ip cut out)",16465,22773,"US","ip(ip)",1,,,,,
>
> ---- end complaint ----

I've ran all the required softwares but no rootkit was found. Is it possible that ShadowServer gave false alarm? Or is the virus hiding so well?

I've attached all the logfiles required, except TDSSKiller, it didn't find any infected files.

Thanks!

 

Ok thanks.
How did you know if I may ask?