vacuum full failing in 7.3

Hi, everybody!

I am getting a weird failure, trying to vacuum a table in 7.3 - it says
"ERROR: Index pg_toast_89407_index is not a btree".
Does it ring a bell to anyone? Any ideas what's wrong? Is it my database
screwed up? I just created it today...
I tried dropping and recreating it... and it seems to be working now.
But still, if it all possible, I would appreciate any ideas as to what
it could be that caused this problem in the first place...

Thanks a lot!

Dima

P.S.

For what it's worth, here is the stack to the place in the code where
the badness happens:

#0 elog (lev=20, fmt=0x81b5f9b "Index %s is not a btree") at elog.c:114
#1 0x0807e18a in _bt_getroot (rel=0x60eba740, access=1) at nbtpage.c:127
#2 0x08080dce in _bt_endpoint (scan=0x82a7830, dir=ForwardScanDirection)
at nbtsearch.c:932
#3 0x08080ad8 in _bt_first (scan=0x82a7830, dir=ForwardScanDirection)
at nbtsearch.c:686
#4 0x0807ef3d in btbulkdelete (fcinfo=0xbfffd240) at nbtree.c:627
#5 0x08163aa3 in OidFunctionCall3 (functionId=332, arg1=1626056512,
arg2=135047316, arg3=0) at fmgr.c:1275
#6 0x0807b470 in index_bulk_delete (indexRelation=0x60eba740,
callback=0x80ca894 <dummy_tid_reaped>, callback_state=0x0) at
indexam.c:579
#7 0x080ca65c in scan_index (indrel=0x60eba740, num_tuples=0) at
vacuum.c:2612
#8 0x080c7f8b in full_vacuum_rel (onerel=0x60ebdfa0, vacstmt=0x82a0768)
at vacuum.c:948
#9 0x080c7e24 in vacuum_rel (relid=89410, vacstmt=0x82a0768,
expected_relkind=116 't') at vacuum.c:827
#10 0x080c7e65 in vacuum_rel (relid=89407, vacstmt=0x82a0768,
expected_relkind=114 'r') at vacuum.c:850
#11 0x080c7765 in vacuum (vacstmt=0x82a0768) at vacuum.c:290
#12 0x081198da in pg_exec_query_string (query_string=0x82a0538,
dest=Remote,
parse_context=0x8294e30) at postgres.c:789
#13 0x0811a9f1 in PostgresMain (argc=4, argv=0xbfffd770,
username=0x8258849 "postgres") at postgres.c:2013