From the Interceptor home page:
http://www.interceptor.novartis.us/dog/en/label.shtml
Storage Conditions
INTERCEPTOR Flavor Tabs should be stored at room temperature, between 59° and 86°F (15-30°C).
Didn't know that 86 degree upper limit! Any home without a/c is going to be over that during the summer at times. And as Kate pointed out, during transport in those trucks, on the highways, I doubt it is in a refrigerated truck! So unless the package is punctured, a short exposure should be OK. (Reasoning that we get that in our homes in summer anyway.)