The search function can't find numbers?

[JonezJeA]

My friend once wrote an article about his birthday. He became 18 and the article his title had the name: 'the first blog as adult, 18 years.'
A month later I wanted to link to it and I gave by the search bar in the link function in: '18 years' and the blog didn't show up.... only if I looked for 'adult'. Is this because that the function can't use numbers are is there more to this story?

[dd32]

works for me: ​http://dd32.id.au/?s=23+year (first entry contains "23 years old")

SQL Looks correct too:

(((wp_posts.post_title LIKE '%23%') OR (wp_posts.post_content LIKE '%23%')) AND ((wp_posts.post_title LIKE '%year%') OR (wp_posts.post_content LIKE '%year%')) OR (wp_posts.post_title LIKE '%23 year%') OR (wp_posts.post_content LIKE '%23 year%'))

If you can reproduce it on a server which you have access to the query log for, I'd be interested in seeing the problem first hand.. but I suspect a plugin might be interfering.. or.. something.