Situation: i go to kynesgrove after sending delphine there months ago- to kill the dragon there and do a bit of the MQ since i was in the area.

Now when i get there the townspeople are fine, but delphine is hostile. I had to keep knocking the crap out of delphine while fighting the dragon.

Reasons to why this happened?
My only conclusion has to be that i got into a misunderstanding with some whiterun guards and that turned into a "tussle" and now i have a 3k bounty in that area. Would riverwood guards- and hence delphine- be hostile to me because of that bounty because they are in the same hold? Or is my delphine just glitching out?

Your whiterun bounty causes this. If you have a bounty there pay it, if not I have no clue

If that is the case, that is poor planning. Delphine - tied with the main quest- should not be in the same object category as generic guards. This could totally screw someone on a console.

This sort of thing can also occur with the members of the Companions - which can equally screw up that questline. Basically, Beth "forgot" to make a faction for specific questline-necessary folks.

This happened to me as well. The guards in Riverwood would attack me on sight the people of Riverwood including Delphine would also attack. So i went to Whiterun and the guards there wouldnt attack me at all even when i was killing the townsfolk (who were for some reason trying to kill me). I had to go into Dragonsreach and attack the Jarl then the guards finally took notice and tried arresting me and when i got out of jail everything was back to normal even the people i had killed came back to life. Btw i play on xbox so it wasnt any type of mod but i hope i could help.