Soooo...

So my husband and I are very open but he still seems to keep masturbating a secret to me until night comes and I'm fast asleep until I wake up to him masturbating the first time I noticed I felt pretty shitty as I'm laying next to him and he is just beating it. but the other night I woke up and noticed I didn't move to see what was going on. he noticed and stopped what he was doing an automatically acted like he was sleeping. I just don't understand. am I alone on this....