How long would you let the green snot continue before you call/visit the doctor?

LO has had thick green snot for most of three weeks now. Some days it's lighter than others but it has run consistently for the last two days. I'm really not sure if it is the same runny nose or different colds (?) back to back. She is teething (K9s) but other than that I don't see signs of any health issues (no fever, tiredness, lack of appetite, cough). LO is almost 2 and in daycare. Daycare says nobody else has been sick and they usually tell me when something is going around.

Do I keep waiting for more symptoms or has it been long enough that I should call?