My DH is the opposite... everytime DD2 cries he is telling me that she wants booie milk. When some of the time she is just wanting to comfort suck. I'd prefer her to do this on the dummy than my boobs. LOL Obviously if she's hungry then I'll feed her.
So yes - some of the time it could be that you DS just wants to suck and may not be hungry... you'll learn to know when he is hungry or when he is just wanting to suck.

Hope this makes sense. Good luck babe. xxx