Changing thumbnail size

Hi, I am redesignig my page. Old design had gallery in 4 columns [gallery link="file" order="ASC" columns="4" orderby="title" size="post-thumbnail"] and thumb size was 140x140px set_post_thumbnail_size( 140, 140, true ); (file name is thumb-140×140.jpg). Now in my new theme main div is little bit smaller so last image from row jumps in next line.
I decided to make thumb smaller so I changed size to 130x130px set_post_thumbnail_size( 130, 130, true ); and rebuilt thumbnails. Now I have thumbs with file name thumb-130×130.jpg, and thats ok, but wordpress gallery still inserts old thumbnails (140x140px). Any ideas?