Pearl is right, don't worry much there.
One of the reasons you lay the centerline out along the crown and following the grain, is that this puts the highest part of the crown down the middle of the bow, regardless of wiggles. So, the bow will be thickest right along that centerline. So, that area will experience the most tension strain on the back. So, the edges (which are thinner) will experience much less. So, unless MAJORLY WEIRDLY violated, you won't have any issues.
Now, if it takes an obviously wild curve in the grain, as around a knot, say, you might have to do something about that. 98% of the time, it's a non-issue.