see this thread for info, but I'd be calling the dealer if it's been 4 months.
www.bzforums.com

Only one key fob?
We bought our BZ4x in March, but we were only given ONE key fob. The salesman said at that time, to contact the dealership in a couple of months and tell them you need another key fob. Huh??? Today we talked with him and he says that Toyota will be sending out the second key fobs directly to...