Is a guy intrested when he keeps looking at does a smile?

We have sorted stuff out hopefully and was at his again I was sitting across from him while he was on his pc checking stuff an I was watching tv and out corner of my eye caught him looking over at me an when I looked at him he kept staring back alittle more before looking back at the monitor then he started speaking to me for abit does he like me i'm thinking of writing him a letter so he knows why i'm being like this as i'm scared of getting close to anyone i'm keen on him but don't want to scare him.