Such things happen on all types of cues, brands, designs etcetera. I wouldn't worry about it. I'm sure OB will take care of this no problem. I don't care who says what about X or Y, in my time I've seen every single brand, including customs have breakage like that. Absolutely no one is immune or can claim a perfect record. We really take it for granted when our cues are subjected to tens of thousands (and many more) impacts and survive without damage. Considering the stress they are under, their track record is pretty darn good compared to the other sporting equipment in other sports.
Now, this is a perfect example of why the whole cue with 2 shaft thing exists. If you are competitive - it's important to have two as close to identical shafts as possible for your playing cue.
The most important criteria (aside from being the same make/model obviously) are:
1. Same brand and type of tip, same hardness. And preferably, have both broken in to the same level with the same radius.
2. Same shaft weight. To many it may come as a surprise that two shafts of the same model and type can weigh as much as 0.75 ounce difference. That alters the balance of the cue.
3. Same taper. This shouldn't be an issue if you don't sand shafts.
For myself, I want the backup shaft to play the same as much as possible. If you gain a lot of experience with a cue, you'll be able to feel the smallest variables. But the idea is to get it as close as possible. In fact, it's best to not even declare one a "back up" and to just interchange between the two often. That way, you are familiar and comfortable with both.
It isn't because the cue in and of itself is critical to your game. Your game is within you. It's so that the difference in feel, weight, balance and squirt does not become a distraction to you - which in turn harms one's game. In the middle of an important match is not time to get a hang of a different cue.
Sorry, didn't intend this as a thread-jacking. Just wanted to share some thoughts.