I've had pretty good relations with Ghandi. We share a religion and I even went to war with him earlier in the game when he asked me to. Now there's an opportunity for a resource trade but whenever I contact him I get a message telling me to stop pestering him! Or he tells me he has nothing to say to me right now. He's supposed to be 'Pleased' with me. What's going on here?

you obviously stopped trading with him (probably another civ's demand you agreed to)

Ah, that'll be it! They don't forget then?
Thanks.

Ah, that'll be it! They don't forget then?
Thanks.

it takes a while
10 turns, usually

10 turns on normal speed. 15 on Epic. Not sure about quick and marathon. Would guess something like 8 and 20 respectively.

would be 30 on marathon

marathon is generally twice that of epic. except for unit creation which is a little quicker than that I think.