If you could send me pictures of the area above the damage, that is the framing of the building and a picture of leak before it was repaired -- I could give you a more definitive answer.
Small amounts of water during smaller storms could have leaked into the building and the framing and some finishes could have absorbed it. There may have been slight staining on the ceiling, but unless a person knows what to look for -- no alrm bels would have gone off.
The storm that caused all the overt damage may have been unusually heavy. There was enough leaking water to do damage. Way beyond the ability of the materials to absorb without damage.
Common sense that if I have to put a bucket under a leak -- it's pretty severe. I should get in touch with the landlord ASAP.
Previous leaks may have begun the damage and the most recent finished it off.
A restoration contractor of forensic engineer could render an expert opinion.
They would need to investigate. Investigate means to open up the repair.
If I were in your shoes the question I'd be asking is, "What would motivate him NOT to report a leaking ceiling?"