I have had panic attacks that have causes chills...I have also gotten very cold after exercising and suddenly stopping and going into a cool environment. Our bodies sometimes can't adjust as quickly as usual when you have many factors going on at once. (I also have gotten chills simply from eating a big meal, when all of the circulation goes to the digestive system, leaving the extremities cold!)
So...all that to say, it could have been one, or the other...or a bit of both. Your body temp dropping quickly due to slowing of metabolism and change of environmental temps...that sparked worry...resulting in some panic.
I don't think it is anything you need to worry about
"Courage is not the abscence of fear, it is feeling afraid and doing it anyway!"
"Worrying does not empty tomorrow of its troubles...it empties today of its strength."
Corrie Ten Boom
Panic Syndrome recovery due to CBT