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