Idk, I've used to travel via train in southern Poland basically everyday for 2-3 years and delays longer than 10 mins I think I could count on the fingers of one hand
The 2.5h one was in Pomorze, but Im from the south too, I think you were lucky. Go on a random big station on infopasazer.intercity.pl and its likely youll see at least one 1h+ delay (granted its low traffic on sunday midday)