If I purchase park tickets (a 10-day hopper) through a website that is still offering tickets priced prior to the rate increase, do these have an expiration? I would like to buy our hoppers at the old price for our trip this October. But.....what if something happens and we can't go this October, and I already spent $900+ on park admission? Will these tickets still be valid if we chose to use them, say, in Spring 2012? Thanks!