Did my landlord violate my privacy rights or am I more in trouble for changing the locks?

I received a phone call while I was on vacation from a repairman that he needed the key to my unit to be let in as the one he was using wasn't working (I changed the locks after I moved in). He stated to me that my landlord had sent out notices to tenants that they were to be coming by to install carbon monoxide alarms in units that didn't have them because it was the law (everything in my unit and the building I live in is electric and this is also stated in my one year lease). He also stated that I wasn't the only tenant upset at the fact that they didn't receive notices. I got very upset and told the repairman that he was breaking the law since I didn't receive any notice. I then called my landlord and she stated that the notices she sent out a week ago just got sent back to her because she was using envelopes with windows and the unit number got cut off. Could I sue my landlord for invasion of privacy or am I more in trouble in violating the lease for changing the locks? She stated that she needed a copy of the key for emergency purposes, but this scenario doesn't seem to fit.