Slimes spawn in the wrong biomes

Please attach either a zip of your world or provide seed and coordinates of the suspected area.

Yes slimes can spawn beneath level 40.

http://www.minecraftwiki.net/wiki/Slime

That's how slimes used to spawn before they were made to spawn in swamps. XD
EDIT: As in, the old behavior wasn't removed when the new one was added on purpose, to make slimes easier to find.