Seeing as physical therapy is generally a requirement for back pain, I don't know that you should automatically be thinking of red flags. However, if he's REALLY excited to go to his physical therapy appointments, then maybe.
Here's the thing though, I'm not sure if your concern is that he might be cheating with the young female in the office - which I suppose is possible - or if you're more concerned that he's happy to be getting some attention from somebody else. Also, how do you define nearly naked? If it's a back massage, he has to come out of his shirt. And pants are really restrictive. Shucks, right now I'm typing in nothing but a toga. I feel free.
This question reeks of insecurity on your part and maybe you need to talk to your "old man about it. You could be upset over nothing. He's still with you right? He hasn't made any attempts to leave you, right? If he's still being loyal to you and hasn't done anything out of the ordinary aside from this "nearly naked" body massage (which I'm guessing are generally almost naked) then I think you're barking up the wrong tree. But once again, you could always just ask him. You've got to trust him until he gives you a good reason not to. A full body massage is rarely that reason. Unless the place has the words "happy ending" in its policy, you are probably okay.
It was written.
This is ridiculous. I have been a certified massage therapist for over ten years, 5 of which I have owned my own business. We have been fighting this stereotype for years now. Massage therapy is a legitimate, PROFESSIONAL therapy. To become certified, one has to go to school (2 years, same as an associate degree) and let me tell you, massage school is no walk in the park. Can you name all the muscles in the body and origins/insertions? Can you look at someones gait (walk) and correctly identify where their problems originate? Probably not. And after school, there are numerous tests, state and national, one has to pass in order to work. Not to mention the continuing education hours required every year. So in a nutshell, a massage therapist is not just a fancy name for prostitiute. We actually work really hard. Unfortunatly there are still some "massage parlors" that use loopholes in local laws to offer adult services. However, unless your husband is going to physical therapy at a "Bath House" where "Full release" is advertised, then you are pretty safe. Physical therapy is usually conducted in a clinic or hospital atmosphere, places that couldnt be less conducive to seducing someone. When your husband goes to the doctor, do you worry that he is going to be seduced by the nurse taking his vial signs?
This lady needs to calm down. I suggest she herself go get a massage, so A) she can relax already!
B) you can experience a professional, theraputic massage and realize that its about as sexy as a ladies annual exam!