Do I really have a reason not to trust?

My boyfriend and I have been dating for a little more than a year and lately I just feel like he's slowly becoming more distant and it's been making me really upset. I've only mentioned things to him once and he told me that nothing is wrong, we're both just busy college students with different schedules. He works a ton, mostly nights, and right now I only see him maybe an hour a day...if I'm lucky. Now, I don't need to be with him EVERY single second of the day but lately I feel like when I'm not with him someone else is. He's NEVER given me a reason not to trust him. He's a great guy and everyone feels that if anyone is to be known for being faithful, it's him. So, why do I feel like this? Am I being insecure? Should I tell him something? Other than this, our relationship is wonderful! He's very loving and we care for each other a lot. I just don't know why I have these feelings... HELP :/