Usually on a M2M lease your landlord can terminate the agreement with a simple 30 day notice. No explanation is required and often LLs do not offer up an explanation because it causes more problem than it solves.

In your case you have a 60 day termination notice. You can try and fight it, but your lease probably states that the LL can terminate with this amount of notification.

Was it related to your painting of the door? Possibly. But it could be just as possible that the LL is vacating the unit to turn it into something else. It is their property.

The PM was probably acting unprofessionally when she attempted to offer up an explanation. Like it was stated before, if your lease says the LL can terminate with a 60 day notice, then they do not need a reason at all, which is the reason they did you a favor and gave you a no cause notification. A For Cause notification would probably hurt your ability to rent in the future.