If you used the method that lots of us do...where you just wrap the screws masking tape rather than pushing the ferrules down into the wood, it could be that there was enough wiggle room that you didn't see the problem.

With a nice finish on it, you probably don't want to plug and re-drill...although it would not show much since it's under the bridge.

The only alternative I can think of is that you may be able to use a rat-tail file to widen the hole in the bridge where the post goes.