What Savage said.
Some low pressure loads tend to not expand the brass sufficiently to seal the chamber from slight blow back. Unless it is extreme, it is really not an issue. The one thing I would be concerned about is brass bulging to the point it becomes hard to chamber, though if it is working OK in your gun, then there is no problem. I don't know if brass life would be effected much. In a bottleneck cartridge, brass will tend to flow when you full re-size as opposed to neck size only, eventually weakening the web of the brass. This kind of brass flow is much much less in a straight walled case. When full length re sized straight wall cases eventually fail, it tends to be higher up on the case body, usually a slight crack, but not at the case web (Base)
Larry