As I understand it, when people use the Pen they sometimes keep them in their purse or bag to carry with them for up to 30 days and they are fine. I have even heard of people leaving the vial on the counter. Now understand that a person would go through a vial or pen a lot faster than a cat, so I definitely wouldn't do that, because you will need to use the vial longer than 30 days. But I guess there is also a possibility that it won't last as long as it was at a constant temperature. My thought is if you start getting wonky numbers for no reason at all then I would think about starting a new pen.
