I've had this happen to me as well, several times now. I never complained because it's only a minor inconvenience, but it's a regular thing: especially the coffee and forest fruit bars seem to be affected by this, but I've seen it with most flavors already.
As far as I can tell, it's usually a few bars that are really oily, and the rest of the same box tends to be only slightly oily. The few "bad" bars definitely mess up the cleanliness of the entire box, though... They are still sealed properly, just oily on the outside as well as the inside (the affected bars are definitely oilier inside as well!).
I'm fairly certain this is an ongoing problem, which started with the latest recipe change. It's been about 30-40% of all boxes of bars I've ordered since that change I think. Other times, the bars are much dryer than usual and contain much less oil. It seems to me like whatever is supposed to ration the amount of added oil per bar is sometimes distributing it unevenly across the batches.