Is infants snoring a concern?

It depends. Depending on how severe the snoring is and whether it sounds like your baby stops breathing briefly, it could be a problem. Record audio and video of the snoring, then make an appointment with your baby's doctor to examine the baby; bring the recording with you so the doctor can evaluate it. Additional testing may be needed if the doctor feels the snoring is severe enough.
Yes. He may have develop an allergy which cause obstruction of the airway.
Keep in mind... .... That the n.P. Mentioned in your comment ( i assume you mean a naturopathic physician) has little or no formal childcare training. I am unaware of a pediatric naturopathic school of education, corresponding to a true pediatric residency. Thus their knowledge regarding a child's health is no better than a lay person's.Snoring in an infant can be normal, but may be a problem. See pediatrician.