Seq scan of table?

I am trying to tune my database and I discovered one select that does a
seq scan on a table but I can't see why... All the join fields are indexed
and I am returning just one record, so no sort is done.
Does it just pick seq scan for the heck of it or is it a reason?

Regards,

BTJ

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Bjørn T Johansen (BSc,MNIF)
Executive Manager
btj(at)havleik(dot)no Havleik Consulting
Phone : +47 67 54 15 17 Conradisvei 4
Fax : +47 67 54 13 91 N-1338 Sandvika
Cellular : +47 926 93 298 http://www.havleik.no
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