As you can fully appreciate, we live in situations without precedent, and a large number of effects will only be understood in the following years. There is a natural tendency for the nasal tip to rotate down in certain nasal configurations. Typically, if you look at your parents and notice that the nasal tip has dropped slightly over time when comparing their photos in youth and later in life, there is a possibility that it may affect you irrespective of external pressure. One could assume that the external pressure could make this problem happen sooner, but there is no scientific observation to back this up. If you can mould the mask over the bridge and direct the top elastic strip high on the head, it will reduce the tension that the mask applies over the nasal tip. Even if the mask would not produce a negative impact despite long hours of use, it may make you feel more comfortable if the pressure is on the nasal bridge then if it is on the nasal tip.