Not necessarily. It depends on a bunch of factors...the couple that come to mind at the moment:
Where/How they are stored? (Are they in an area where they can breathe, not resting on anything metal, a dry, cool, dark area where pretty much all side can be exposed to air.)
Did you use different fragrance oils with each batch? (sometimes that small variance can have an effect on things.)
Are all of the oils the same age in your batches or did you open a "new bottle" of whatever oils to make more batches etc.?
Certain oils, etc. DO have more of a probability of DOS, etc. as well so it is POSSIBLE that your formula may need some tweaking. It's just not an "absolute."