Horrific time for getting 1 record from an index?

Postgres 9.1.9.

explain analyze select min(insert_time) from cnu_stats.page_hits_raw ;
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------
Result (cost=0.12..0.13 rows=1 width=0) (actual time=257545.835..257545.836 rows=1 loops=1)
InitPlan 1 (returns $0)
-> Limit (cost=0.00..0.12 rows=1 width=8) (actual time=257545.828..257545.829 rows=1 loops=1)
-> Index Scan using page_hits_raw_pkey on page_hits_raw (cost=0.00..5445004.65 rows=47165480 width=8) (actual time=257545.826..257545.826 rows=1 loops=1)
Index Cond: (insert_time IS NOT NULL)
Total runtime: 257545.881 ms
(6 rows)

I checked and there were no un-granted locks... but I have a hard time believing it actually too 257 seconds to get 2 pages (one index, one heap) back from our SAN.

Am I missing something here?
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Jim Nasby, Lead Data Architect (512) 569-9461