Corrupt RTREE index

I have what appears to be a corrupt RTREE index.

The first query shows that of the fifteen records I'm looking at, every one of
them has the "@" based condition showing as true. The second shows one record
that really ought to be there not being listed.

I just tried the second query with enable_indexscan = off and the missing
record reappears. So I guess this is a corrupt index.

This is 7.4.6 but the database was initdb'd with an earlier 7.4.

Should I REINDEX or should I keep this around for forensic study?

slo=>
 SELECT distinct store_id, geom2 @ box '(-72.7956933266664,46.041219387024),(-74.3364602689304,44.9613057801126)'
   FROM store_location
  WHERE earth_dist(geom, -73.5660767977984, 45.5012625835683) <= 60

;
slo=> slo-> slo-> slo-> slo->  store_id | ?column?
----------+----------
      504 | t
      597 | t
      909 | t
     2841 | t
     2940 | t
     2997 | t
     3423 | t
     3438 | t
     3641 | t
     3656 | t
     4057 | t
     4487 | t
     4489 | t
     4490 | t
     4493 | t
(15 rows)

slo=>
 SELECT distinct store_id, geom2 @ box '(-72.7956933266664,46.041219387024),(-74.3364602689304,44.9613057801126)'
   FROM store_location
  WHERE earth_dist(geom, -73.5660767977984, 45.5012625835683) <= 60
    AND geom2 @ box '(-72.7956933266664,46.041219387024),(-74.3364602689304,44.9613057801126)'
;
slo=> slo-> slo-> slo-> slo->  store_id | ?column?
----------+----------
      504 | t
      597 | t
      909 | t
     2841 | t
     2940 | t
     2997 | t
     3423 | t
     3438 | t
     3641 | t
     3656 | t
     4057 | t
     4487 | t
     4489 | t
     4490 | t
(14 rows)

--
greg