what do you mean, "correct" or "incorrect?" if you deleted some rows, the AUTO_INCREMENT number is not set to a lower value -- it always goes up. this is how it's supposed to be. so i assume you're still getting a number, but it's just higher than you think it should be? then, yep, that's the correct behavior.
if you DO want to reset the AUTO_INCREMENT back to something lower (make sure it's a least 1 more than the currently highest value), use ALTER TABLE:
ALTER TABLE table AUTO_INCREMENT=n