I wouldnt worry too much about it actually.
You are not lactating if the fluid is clear.
I've had this happen before when not on cycle and it is related to hormones but unless the gland beneath is swollen and perhaps tender, chances are nothing you are doing is aggravating it too much. Your hormone levels will rise and fall all the time in response to just about everything: stress, diet, sleep, overstimulation, other medication, etc. You may have had a surge in testosterone for some reason, which left some extra estrogen lying about after it subsided.
I recently had one swollen gland beneath my left nipple and it was slightly sore to palpate and squeezing discharges clear fluid as well. In my case it was steroid/estrogen related (I believe my arimidex may be bad) but a few days of dosing aromasin reduced the swelling almost entirely.
Of course the safest bet would be to see a doctor but I would just keep an eye on it. If you had squeezed it a year ago you may have gotten some beads of fluid appear on your nipple, chances are you just never tried until now. I wouldn't be surprised if there is some sort of sebum or other fluid sitting in those glands all the time.