Has the connection gone?

I started dating this guy middle of August, he works away so was only home until beginning of september and is not due home til mid november. he messaged me constantly for a while, saying he missed me, sending me sweet messages and then he paid to fly me out to be with him for a weekend. This all sounds great and it was amazing until this point... since i have been back, he has become distant. he hasnt said he is missing me once and the sweet messages have become occasional. he does text me every morning and every night to say goodnight and sometimes throughout the day and will respond to my messages if i message him any other time. i have asked him why he has become a bit distant and he said he finds it hard missing someone when he has to work and he doesnt know what he wants.. am i reading too much into this or have i got reason to worry??