Sometimes when seed potatoes are subjected to cold temperatures and then very warm temperatures they respire, which makes them look wet. They will dry out and does not affect the growth of the potatoes. This shows that the seed potatoes are reacting as they should under these conditions.
If you are worried that the potatoes may have been frosted keep them at room temperature for 2-3 days. If the seed potatoes have been frost damaged, they will start to deteriorate, going soft and then rotting, exuding moisture when pressed. Cutting a frost damaged potato will show the inside turning black, like a very bad bruise. If the tubers are still in good condition after this time, return them to a cool, light, airy, frost free place.
In our tests it has been found that the packaging will protect the potatoes down to at least -4ºC but we do avoid dispatching our seed potatoes in very cold weather.