Show intent on going to 2nd

[bsnalex]

A few weeks ago I had this come up--

BR safe at first on the throw and then gently turns into the infield - he was probably a yard overrun from first and maybe 1 - 2 feet infield off the baseline. What I noticed when he was safe is that he did not continue his overrun nor peel off to the right. His left shoulder turned inward and to me, while he didn't show blatant intent to go on to 2nd he certainly made no point of showing me as a blue that he WASN'T going to 2nd.

At that point first baseman turned around and tagged him and I called him out on the tag at which point I got some jaw from one of my fellow umpires who was not working the game, but observing.

He told me (in front of both teams!) that I got the call wrong and that the runner should only be out if he showed intent on going to 2nd. I felt that as he turned his body inward that was intent enough for me. I pulled the player aside after the inning and told him (umps do this as it's a small league and we get alot of new players) that to avoid any doubt run straight thru the base and when you return, make sure you turn your body to the right and walk back to the base on the orange side of the base.

Can I have any thoughts on this? We use ISF book.