Why isn't he calling?

I have been seeing this guy for around a month now. At first he texted me everyday, and we hung out almost as much (he initiated most of it). I was afraid it was too much so I talked with him to make sure he wasn't feeling smothered. He said no and he was having fun, but after that he hasn't been texting me as often and he asks me to hang out like once week. I'm wondering whats up, why is he not being as attentive as before? I don't think anything big with our relationship is wrong because we both agreed to tell the other if we felt things were going south, but I don't really know whats up.