FULLTEXT index ignored in BOOLEAN MODE with 'number of words' conditional
I have very bad news for you.
Unfortunately, that is the correct behavior.
The MySQL Query Optimizer tends to get sidetracked very easily when using a FULLTEXT index.
I also have very good news for you.
I wrote about this in StackOverflow on how to get around it.
You may have to nest your original query in a subquery and return the MATCH function as a column. Then, evaluate the MATCH column outside of the subquery.
Instead of your query
select * from seeds  WHERE  MATCH(text) AGAINST (&quot;mount cameroon&quot; IN BOOLEAN MODE) = 4;

you must refactor it into something like this:
SELECT B.* FROM
(
    SELECT id,MATCH(text) AGAINST
    (&quot;mount cameroon&quot; IN BOOLEAN MODE) score
    FROM seeds
    WHERE MATCH(text) AGAINST
    (&quot;mount cameroon&quot; IN BOOLEAN MODE)
) A
INNER JOIN seeds B USING (id)
WHERE A.score = 4;

Give it a Try !!!