How do you know if another tenant is following you / where is the line?

I recently moved into my new apartment (which I love overall) in mid May. I’ve had a few odd encounters with another tenant:

1. Left a note on my door saying “Your so beautiful want to get to know you fr” followed by his number 🙄

2. Follows me as I walk my dog, will walk various dogs as I walk my dog (different dog every time), seems like he’s going to approach me and then swerves

3. Comes outside his place and stares at me as I drive in and out of the complex

4. Already asked if I have a boyfriend/called me beautiful

5. This weekend was especially weird. I guess he somehow saw that my boyfriend and I were in the pool (I was in a tube in a bikini and boyfriend holding my tube) and he literally got in the water and started trying to swim closer to us all by himself

(I didn’t tell BF it was him bc I didn’t want him to cause a scene unless something actually popped off)

Should I be concerned or just let it run its course? It’s been about a month now of this.