I don't believe it is abnormal to get some leakage of oil out the breather. The question is, how much? I put the breather tube in the neck of a cola bottle to catch drips and breather waste while traveling. It has helped reduce the amount of oil and dirt build-up around the breather area also, keeping the engine, under side of the coach, and toad cleaner. There are actually OEM kits built to mount around the breather to help minimize breather oil effects also. I'm cheap and just use a bottle I straped in. One of the primary causes I have noticed from RV manufacturers is that the dip stick may not be calibrated precisely and often RVers over-fill with oil. It doesn't take much over-filling before excessive breather "drippage" occurs as a result of the normal blow-by action. Therefore, you might try running your engine a little lower on oil, say about the lower end of the dip stick markings and see if the amount of oil drippage decreases.
'01 Alpine 36 FDDS