Exception to Coverage Until Age 26?

A recent retiree from a large US based corporation was told that her 25 year old son was not eligible for coverage under the retiree health plan because it only offers coverage until age 25 rather than the age 26 as in the active employee plan.

I was under the impression that the ACA required all plans to offer coverage until the child's 26th birthday. Is this incorrect, or is there some exception I'm unaware of?

Off the top of my head, I do not believe that the age 26 rules apply to retiree health plans.

The to age 26 does not apply to retiree only plans.

Thanks for the replies!

Some employers have not been careful to separate their retiree health plan from their active health plan.  For example, they may put both in one wrap plan and file one 5500.  If enough money is involved, and if the facts are right, you might be able to argue the retiree health plan and the active plan are one and the same, and thus the retiree health plan would be subject to the ACA.