[TR] TR3b windscreen cracked, again!

[TR250Driver at aol.com]

Guys,
 
I walked out Friday morning and it was cracked from  just below the top 
screw, driver's side all the way to the bottom. Nice  clean break. Disturbing 
thing is that the ole lady TR3b has  cracked her windscreen in the same spot 
a few years back. Like the exact  same thing.  No warning, can't say any 
pressure was put on it. 
 
Last time it was the nite before a TRA  Concours.  Went down the morning of 
and there it was, cracked! This  time same thing.  The only thing I can 
think of is I did warm up the garage  the day before to work in there to 68 
from around 32 degrees and let it cool  down again that nite.   What am I doing 
wrong?  I have heard of  the screws being to long and chipping the glass 
but I was real careful with  them.  
Woe is me,
Darrell