S.H.
No kid is accident free.
Even if a kid is punished for it... they WILL have accidents.
He is only 2.5 years old.
ALL kids, have accidents. Daytime or night time.
Its normal.
And at this age, they do not have 100% fully developed organs or 100% fully developed impulse-control yet.
Even 3,4,5,6 year olds, have accidents.
At my kids' school, the health room even stocks extra underwear and clothing, for kids to change into if they have an accident. It is no biggie and the Teachers do not make a fuss about it.
There is NO need to punish or make a child feel bad or embarrassed about an accident.
This is childhood. Kids have accidents.