What Causes Absence Of Surge While Having A Regular Menstrual Cycle?

Hi doctor, I have been using clearblue digital OPK for 4 months now...the first 2 months I detected the surge exactly when I expected it ( I have a 31 day regular cycles, LH surge was detected on the 22nd of Nov and Dec) however for the past two months of Jan and Feb, I did not detect the surge and I've still had my regular period. What could eb causing this?is my situation alarming?should I go see a doctor?