Hmmmm, not sure! Mine still says 40......... Maybe a glitch? Capitalise on it before they disappear!

Are you perhaps getting mixed up between your allocation of free listings, and your sellling limit?  They are not the same thing.  A selling limit is a ceiling on the number of listings you can put up in a month, regardless of whether they are free or paid listings.  Free listings for non store holders are generally 40 per month, with extras from time to time when bay feels like dolling them out. 

Be careful though, if you have a selling limit of 200, and only 40 freebies available you will be charged for the other 160.  To check your free listing balance, scroll all the way to the bottom of your MySelling page and you will see them listed.  It shows how many you were given how many you have used, how many are left, and when they expire.