Testing for Mold Behind Walls

Would you recommend a mold test in an area where there was a one or two time roof leak, that was fixed as soon as the problem was discovered, and which dried on its own? I’m told that I would have to do an air test behind the wall in this circumstance to determine if there is mold. Why is this? If there was a real problem would it not be clear in an air test for the mold in the room? If I have to go to such lengths to determine if there is a problem, perhaps there is no problem at all? Any thoughts would be appreciated.

Doing a air test behind the wall should be as easy as doing one in the room. One easy way is to take off a switch plate or outlet cover to insert the adaptor behind the wall. If you do not have any of those on the wall and you have baseboard heat just punch a small hole under the baseboard cover and do it there. Remember to take at least 2 samples, one outside as a control.