Would you approve use of these PCBs??? Delamination issue
The fact that they delaminated in only a year calls into question the quality of the workmanship, regardless of the fact that they were in storage. Like you said, if they delaminate in storage they most certainly would delaminate in the field, and in a safety-critical application this is absolutely unacceptable. I would agree with John D that these should be scrapped (depending on the cost, you may be able to work out a partial refund from the supplier) and order new ones from a reputable source. Also, if you have any authority to do so, I recommend pushing a redesign to hatch the copper pours.