Don't say it's not like they will eat each other because it has happened.
There are many reasons why it isn't advisable to house 2 together. People have and do with no issues but it really isn't a great idea. They may be doing fine but you're still taking a risk.
Also, "cuddling" together is only happening because they both want the best hot or cool spot. That or the male wants to breed.
Remember, these animals are 100% wild instinct. They do not lay together because they like it or want company. Snakes don't have that capacity for emotions. They lay together for breeding or heat regulation. They're competing most likely.
Clean bill of health? So your vet took a mouth culture to completely rule out RI? You waited days or a week for the lab results before putting them together? Aside from that there are diseases they can have which there is no test for. Often no symptoms, and a 100% chance of death as the outcome..
Housing together is not recommended and that is obvious but you will get torn a new one here if you do not practice quarantine procedure when getting a new snake. Housing together has actually been done by some breeders here and to each his own on that one.. Quarantine on the other hand, shows lack of responsibility. It has happened that people have lost entire collections due to improper quarantine and the new animal had a disease that showed no signs or symptoms.
Just some food for thought..