Dan,
It is currently 29 degrees here and with only the support on the base of the windshield, my top is not pulling up on the windshield frame at all. My top was fitted during the summer and does fit tight. I decided to store the car with the top on, just in case I get a warm spell, figuring that it would be easier than trying to install a cold top. 60 degrees really is not that cold, I had the car out for a spirited run earlier this week in 60 degree weather wearing nothing but a t-shirt and a grin. The top did not pull on the windshield at all, even at 5200 rpms.
How tight was the top fitting originally and how hot was it when you first fit the top? I have installed mine when it was cold out and it was a struggle at times, but doable and I have never seen the top pull up on the windshield frame, except once on the highway and I will leave it at that
It might be that you will need another brace...?