spurious "Service Unavailable"

On CURRENT Revsion 255706

I am trying to rebuild a bunch of ports in screen and I'm getting the
string "Service unavailable" in the output between the package creation and
the cleaning phases for each port:

===>   Generating temporary packing list
install  -o root -g wheel -m 555   dialog4ports /usr/local/bin/dialog4ports
install -o root -g wheel -m 444 dialog4ports.1.gz  /usr/local/man/man1
===>   Registering installation for dialog4ports-0.1.5_1 as automatic
Installing dialog4ports-0.1.5_1... done
===>  Building package for dialog4ports-0.1.5_1
Creating package for dialog4ports-0.1.5_1
Service unavailable===>  Cleaning for dialog4ports-0.1.5_1
--->  Cleaning out obsolete shared libraries
--->  Reinstalling 'm4-1.4.16_1,1' (devel/m4)
--->  Building '/usr/ports/devel/m4'
===>  Cleaning for m4-1.4.16_1,1

Is this dangerous?  Anyone know what's making that happen?

thanks,
dave c