Look what I found - problem?

[bigi]

I'm sanding my decks in preparation of re-doing the non-skid. I pulled the hatches to work on them. Things looked generally good under the deck. But, I found some delamination around the stringers. Not sure if it's a problem or not. Is it superficial or does it need to be addressed right away. Is it a sign of bigger problems?

Photos are attached.