Index not being used

I'm confused. Shouldn't this index be used?
(It's running on v7.4.7)

airburst=> \d stats2
Table "public.stats2"
Column | Type | Modifiers
-----------+-----------------------+-----------
lab | character varying(30) |
name | character varying(50) |
status | character varying(40) |
eventtime | integer |
username | character varying(30) |
pkey | character varying(60) |
Indexes:
"stats2_etime_index" btree (eventtime)

airburst=> \d stats2_etime_index
Index "public.stats2_etime_index"
Column | Type
-----------+---------
eventtime | integer
btree, for table "public.stats2"

airburst=> explain select count(*) from stats2 where eventtime >
1167638400 ;
QUERY PLAN
-----------------------------------------------------------------------
Aggregate (cost=185247.97..185247.97 rows=1 width=0)
-> Seq Scan on stats2 (cost=0.00..179622.45 rows=2250205 width=0)
Filter: (eventtime > 1167638400)
(3 rows)

Thanks,
Ralph