stats collector dies in current

I see stats collector processes die in current when I suspend
postmaster then put it in background from a terminal:

$ ps x
:
:
21638 pts/1    S      0:00 /bin/bash -i
30525 pts/1    S      0:00 postmaster
30527 pts/1    S      0:00 postgres: writer process   
30528 pts/1    S      0:00 postgres: stats buffer process   
30529 pts/1    S      0:00 postgres: stats collector process   
30530 pts/1    R      0:00 ps x
$ fg
postmaster

[1]+  Stopped                 postmaster
$ bg
[1]+ postmaster &
LOG:  statistics collector process (PID 30528) exited with exit code 1

Is this normal?
--
Tatsuo Ishii