Agreed
You always take a risk buying from a shop. That is why hobbiest breeders that you know and trust are so crucial to our hobby. I would go with the snake getting overheated before I would jump to some form of a infectious disease that manifests it self like IBD in colubrids. That is why I make no quams paying a little more for my animal and building relationships with the breeders I want to work with. I am not sure you are being too paranoid but I think you have to take a retail store for what they are and you alway take a risk of picking up something bad from a place that has no quarantine procedures in place, know what I mean.
Chuck