backends rereading postgresql.conf

In answering the question about SIGHUP and pg_hba.conf, I was surprised
to learn from Tom and postgresql.conf is reloaded by backends on
postmaster SIGHUP, at least for certain configuration settings.

It this new behavior? I thought postgresql.conf changes only were seen by
newly spawned children.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026