Strange obstruction play

[jchamp]

I've done about a season and a half of softball before this baseball play a couple weeks ago, in my first baseball game. It's JV, Fed rules.
R2 & R3, 1 out, batter shows bunt, F3 & F5 charge. Ball trickles down first base line. F3 fields it after BR passes him and with no play at home, he turns to throw to F4 who is late covering first base. His throw goes into foul territory, and F4 jumps across BR's path trying to make the catch, making a play on BR that would make Ray Lewis smile, knocking him down into the coach's box. F9 grabs the ball and tags him on the leg before BR could scramble to the bag.
My call: Obstruction on F4--while accidental, he was out of his place, blocked the runner from reaching the bag, would never have gotten the ball before he could make a tag, anyways, and was five feet off the bag towards home when the collision occurred.
Def. coach argues that it's a "no call" and that I need to let the play work itself out to see what happens.
What I think I screwed up was, since I made the Obstruction call, I'm not sure if R2 who had made it to third base should have gone back instead of making it home after the fact. But I'm pretty sure the obstruction was the right call. I wasn't able to get a good reading from talking to subsequent partners, except that one said if I was certain my call encouraged player safety, it's what I should call.