Tenant locked out, should I charge a fee?

[Samantha Klein]

Hi everyone, around 9PM last Friday night, my tenant texts to say she locked her keys in her apartment and asked if I would stop by to let her in, this was 9PM at night but I only live 5 min from the property so I agreed. I inherited this tenant and she's been on time with rent, however, she's kind of evasive, she tried to avoid me for the first 3 weeks when I took over the building. I would say my relationship with her is good however there is a $50 lock out fee in the lease and I feel like I should charge it because I want her to know that I am holding her feet to the fire with the agreement but on the other hand, I did not mention any fee when I opened her door and don't want her attitude towards me to change over $50, what do you think?