Is he not trying to seem clingy?

The guy I really like, works for anywhere between 8-12 hours a day, 4-5 days a week. He gets online almost every night after work, before going to sleep. Once or twice a week, he IMs me & tells me "good night" before getting offline. Why does he only do it maybe once or twice a week? He has no idea how happy it makes me when he tells me good night.