change in relationship... would you be upset by this?

my bf of 2 years is 1500 miles away. for like 1.5 years, when we are not together, we would have skype sessions that sometimes involved masturbating together. for a couple months, he was super into it and would request it quite often and wait for me to get home before he jerks off.

the last couple of months (like 3-4 months), he's been losing interest in it. he now prefers porn and his own privacy. when we are together, the sex is still amazing but it's just the time we're apart that we don't have these skype sessions anymore and i'm starting to feel insecure.

i asked him about it today and he said he's just been thinking it's a little weird to do skype like that. and that lately he's just been more in the mood for "him time" with good old porn and privacy and that it has nothing to do with me and our relationship.

should i be upset about this change in our long distance relationship or is it normal and fine?