I'm not quite sure that this is correct.

Based on what I've read, the mileage cost for an award ticket on hold can increase at any point until the award is actually redeemed.

There is also the following footnote at the bottom of the e-mail confirmations that are sent after an award ticket is put on hold that would seem to confirm this:

"1 The mileage is subject to change until the ticket is issued."

Personally, I wouldn't take any chances.....especially if the specific dates were important and/or if it's a "prime" route.

A.J.