Last time I take her advice?

[Dazzbrew]

Maybe if John Palmer says it you will belive it. See below

http://www.howtobrew.com/section1/chapter6-5.html

Im not suggesting that you shouldnt use the method of rehydration as directed on the packet, what I AM saying is that rehydrating us05 at 35-40c DOESN'T ruin your yeast.

edit: further comment.