AppleFileServer strange behaviour

I've got a strange issue with AFP on a new server installation.

Hardware: Mac mini server (Mid 2010) — this had SLS installed originally

Software: erase and install of OS X 10.8.2 + Server 2.1.1 (+ WGM 10.8 and CarbonCopyCloner — nothing else)

— Runs DNS (checked with changeip, lookup on the server + a client)

— Users and groups were migrated from a different 10.7 installation (using WGM export/import), they have their network home on the server.

— SACLs are set to enable access for AFP to all users

— A bunch of AFP/WebDAV shares were added using File Sharing pane of the Server.app (no SMB sharing, some with guest access, one as a network home)

— Open Directory was started using the Server.app

— Client Macs were bound to the OD

Users are able to log in using SSH, AFP and standard GUI login on client Macs. Everything seems fine so far.

PROBLEM: system.log displays hundreds of messages from AppleFileServer like this:

5.11.2012 7:56:19,477 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:19,609 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:19,740 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:19,869 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:19,998 AppleFileServer[222]: Logged out 0x7fea51058a00
5.11.2012 7:56:20,129 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:20,258 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:20,388 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:20,516 AppleFileServer[222]: Logged out 0x7fea51058a00
5.11.2012 7:56:20,747 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:20,878 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:21,013 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:21,146 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:21,288 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:21,525 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:21,660 AppleFileServer[222]: Logged out 0x7fea51058a00
5.11.2012 7:56:21,805 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:21,941 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:22,079 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:22,212 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:22,348 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:22,483 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:22,622 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:22,866 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:23,006 AppleFileServer[222]: Logged out 0x7fea5180a200
5.11.2012 7:56:23,141 AppleFileServer[222]: Logged out 0x7fea5180a200

These messages do appear when someone is logging in, but may appear also at other times. Does anyone have any clue to what's going on?