Unfamiliar recovery message afer server crash

For unknown reasons, our PG server died overnight. (PG 7.4.2, RedHat 8,
ext3 ordered data mode, and battery backed RAID5)  When it came back up, I
saw an unfamiliar line in the recovery output from Postgres:

Apr 20 11:28:14 postgres: [6203] LOG:  database system was interrupted at
2004-04-20 05:50:59 CDT
Apr 20 11:28:14 postgres: [6203] LOG:  checkpoint record is at 7C/CF55FB6C
Apr 20 11:28:14 postgres: [6203] LOG:  redo record is at 7C/CF55FB6C; undo
record is at 0/0; shutdown FALSE
Apr 20 11:28:14 postgres: [6203] LOG:  next transaction ID: 9374951; next
OID: 158516389
Apr 20 11:28:14 postgres: [6203] LOG:  database system was not properly
shut down; automatic recovery in progress
Apr 20 11:28:14 postgres: [6203] LOG:  redo starts at 7C/CF55FBAC
Apr 20 11:28:17 postgres: [6203] LOG:  unexpected pageaddr 7C/C7A0A000 in
log file 124, segment 207, offset 10526720
Apr 20 11:28:17 postgres: [6203] LOG:  redo done at 7C/CFA09F7C
Apr 20 11:28:20 postgres: [6203] LOG:  database system is ready

What's the significance of the "unexpected pageaddr" item?