We have to see why people become atheist/agnostic/non-theist and why people may become religious and why people change religions. If the factors for the first are increasing in general, then maybe. But yeah it could just be an age thing, if the factors that make people turn to religion become more common as one ages.
A big cause of doubt/faithlessness has to do with the actions of religious institutions, such as their stances against homosexuality, women, minorities (when applicable), and how difficult it is for those same institutions to cover up such scandals. Additionally, greater access to information allows the curious or doubtful to compare their religion to others, as well as historical sources and sciences. It probably goes without saying on this board, but religions don't tend to fare very well when their supposed answers and explanations for things are exposed to facts and criticism.
As far as changing religion goes, my understanding is that it tends to be more a case of a person's previous religion not providing sufficient answers or agreeable moral guidance.