Mild stenosis often is do to some calcification of the valve's orifice (opening). Usually not serious, if and when it is serious the left ventricle pumps against the higher resistance of the narrow opening and LV can/will enlarge. An enlared LV can lower contractility and reduce cardiac output and cause arrhythmia (irregular heartbeats). As one ages it is not unusual to have some calcification of heart valves. Not considered medically significant and shouldn't be of any concern.
Thanks for your question, and if you have any followup questions you are welcome to ask. Take care.