My experience with WES is they are VERY VERY VERY specific on their criteria for accepting documents. They do not under any circumstance deviate from their requirements, period. So...as long as the docs you are trying to send meet their criteria, its worth trying to send IMO, regardless of the date. If not, scrap them and get new ones that do meet their criteria.
Also, I would highly suggest sending them via courier with tracking. If you call in to WES and ask them to check to see if they rec'd your docs, you will get nowhere with them unless you can prove your docs were delivered to them.
Good luck...it took me 3 months to get a high school transcript to them that they'd accept because my high school uses a third party service to manage all their transcripts.