Featured Image appearing in Header Area on Certain Posts

Hello All,

I am using the Twenty Ten theme. For some reason on some pages the featured image is appearing on some posts in the header section (unwanted) and on other posts it is not (as I want it). see below;

Correct: http://www.kilmallockgaa.com/2012/05/family-fun-race-night-2012/

Incorrect: http://www.kilmallockgaa.com/2012/05/kilmallock-trio-after-recent-win-over-dublin/

I have nothing chosen under Appearance/Header on the admin dashboard.

Any ideas would be grateful?