Do "unused" miles really roll into next MDX lease?

I have a 2011 MDX coming off lease in 4 months. Received brochure from Acura stating that "unused miles from current contract" will be rounded up and rolled into next Acura lease.

Is that true or just some kind of sales gimmick where you actually pay for these miles again in the lease price but don't know about it.

We're seriously considering switch to Infiniti QX60 but I will likely have 10,000 miles which will not be used.

Please let me know. Thanks.