Just a bit of a lesson in general. While you guys are probably doing the right thing by thanking the coach for any help and informing him of baseball plans - you don't go out seeking praises and pats on the back. Yes it is nice to be told good job and have people that are also excited for you, but that is what friends and family are for. Nothing wrong with letting the coach know, but don't go searching for validation. He will be receiving it in the form of interest and eventually offers.
That being said, most high school coaches are just teachers who played baseball. Not all were pro stars, college stars, or high school stars. In fact many don't know what they're doing all that well. I don't know the situation but there are plenty more teachers who coach than coaches who know their way around a recruiting trail.
Maybe he is waiting for more news other than "talking" to schools. If he doesn't follow up with you/your son next time he sees him I would just chalk it up to a grumpy old coach