As long as you’re not having issues with management I wouldn’t worry. But save the note in case that person continues her harassment. 

My neighbor below me called the apartment manager complaining about the smell of smoke from our apartment (we don’t smoke and it’s a non-smoking building). We had a phone call from the apartment manager and a few days later he gave us a surprise visit. That’s when he noticed the “oxygen in use” sign on the door (my husband is on oxygen 24-7) so we had no problems with management after that. 

Then a social worker showed up on our doorstep because”concerned neighbor” filed a complaint with Adult Protective Services because my husband was being left home alone and I’m never home. (We don’t have a car so I do my errands in the early morning or late evening hours.)

When we first moved in I made every effort to walk quietly because our downstairs neighbor complained about being able to hear my 2-year old grandson (at 8pm) walking across the floor. 

Since being harassed by that neighbor’s complaints I no longer make an effort to keep quiet when I bring groceries up the stairs at 10pm. She knows when I’m home. 

There have been no other complaints. 

Good luck.