I don't think so. It's not too dissimilar from failing to distribute a SH notice (excluding the breach that you mention).
Any chance the notice was posted on the RK site?
Since your ex didn't commence his benefits yet, if you start your benefits before his age 65, your full share will be reduced due to an early commencement. His retirement plan administrator should provide you, upon your request, the calculated amounts of your benefits under scenarios of retiring now and retiring 3 years from now (at his age 65), so you can see what is the reduction, and then decide if you would want to take it.
You did not necessarily "forfeit" any payment amounts as the plan is required to pay you an actuarially equivalent benefit. If you commenced earlier you would have received smaller amounts as they are expected to be paid over a longer period of time.