[Systrace] httpd and unknown user

[openbsd at wp.pl]

hello,
I try keep apache in systrace but sometimes I have this logs:

Jan 22 20:46:03 hood systrace: deny user: , prog: /usr/sbin/httpd, pid: 
14227(0)[28469], policy: /usr/sbin/httpd, filters: 93, syscall: 
native-fsread(188), filename: /htdocs

I try with 'user =' define and without this.

when can be bug ?

thanks
:nobody