Swallowed a piece of bone without chewing it..should I be concerned?

I let Rio him his first chicken piece today..about an hr ago. It was the smaller part of the drumstick..sorta looks like a smaller thigh..not sure what it's called. I was holding the bone lightly while he was chewing on it. Well...he broke off a piece and just swallowed it..did not chew it down at all. I am extremely nervous. The piece was prob about a half inch to an inch big, and about a half in wide. Should I be concerned?? Could this pose a threat of puncturing something internally or causing an obstruction?? Never feeding bone again..whole bone..he doesn't like to chew..he just gets it in his mouth and swallows. He is a chihuahua, 8 lbs. I'm very worried.