JOIN index/sequential select problem

Hi,
I'm having a minor problem with one of my queries.

inventorysuppliers.id
av_parts.rawpartnumber
av_parts.vendorid
all have indexes.

Why in the world is postgres selecting seq scan on the inventorysuppliers
table when doing an LIKE?  That doesn't make sense to me.

PG version: 6.5 CVS as of monday.
OS: Redhat 6.0, Linux 2.2.6, glibc 2.1
Platform: i386

Running query with explain:
Nested Loop  (cost=440.35 rows=1 width=100) ->  Seq Scan on inventorysuppliers  (cost=11.90 rows=209 width=40) ->
IndexScan using av_parts_vendorid_index on av_parts  (cost=2.05
 
rows=1 width=60)

Running query with last line as:           AND (AV_Parts.RawPartNumber = '6890040')

Nested Loop  (cost=4.10 rows=1 width=100) ->  Index Scan using av_parts_rawpartnumber_index on av_parts
(cost=2.05 rows=1 width=60) ->  Index Scan using inventorysuppliers_id_index on inventorysuppliers
(cost=2.05 rows=209 width=40)

Query:
SELECT  AV_Parts.PartNumber,       AV_Parts.Description,       AV_Parts.NSN,       AV_Parts.Quantity,
AV_Parts.Condition,      inventorysuppliers.companyname,       inventorysuppliers.phone,       inventorysuppliers.fax,
    AV_Parts.ItemID,       AV_Parts.VendorID   FROM       AV_Parts, inventorysuppliers               WHERE
(AV_Parts.VendorID= inventorysuppliers.id)             AND (AV_Parts.RawPartNumber LIKE '6890040%')
 

Thanks,
Ole Gjerde