The above is true! Believe me you have no need to worry. I have had a few escapes here and there, either by them getting away when feeding our when I clean their tub out. We eventually find them, usually in the bathroom. I think they go their because it is a smaller room so it stays warm and humidity is higher in their due to showering. They all eventually die. We even usually keep our house above 75 and they still eventually die off. I have come to believe that they "need" companionship - in the sense that one, they of course can't breed without another, and if they do find themselves in a colder condition they can keep warm by "cuddling". I found this out when I went to pick up some that I had previously given a friend who no longer needed them. I had a bit of a drive and also had to stop at off at a relatives house for a couple of hours, they had to stay out in the car. It was pretty cold outside and I lost a few, but found that the ones that stayed "cuddled" up to others made it till I got home and able to warm them up.
I also have a friend who breeds them, and she has had many accidents including accidently knocking over on of her dubia tubs - hundreds got loose. She eventually found them here and their dead, and there was no infestation problem.
The thought of them getting out and infesting your house is dreadful, but I honestly think it's impossible.
I also suggest not adding any escapies back into the bunch. If you want to eventually add them back then keep them seperated for a while. But you have no idea what they have gotten into while they have been roaming your house, and you do not want them to make your other healthy roaches sick. Plus, I found one and kept it seperated, it died after about a day so who knows if it got into something that could have harmed my other roaches, or if the factor of not having its required needs for living for a couple of days finally payed its toll.