Mould on Canvas?

After a recent trip to NT, we seem to have some mould on the canvas of our CT. We had very heavy dew on a number of days and the inside of the canvas on window flaps and the awning have what appers to be mould. Probably results from the inside of the canvas being wet, then drying very slowly as it was not in the sun.

It all dried out and got no worse, but has left dark blotches on some of the canvas.

This all happened a couple of months ago and since the canvas was dry, we packed the camper away and thought no more about it. After about 5 weeks, I opened the camper yesterday. It has not changed in that time, which suggests that if it is mould, it is dead, or at least not active.

Questions:
If the mould has been dormant for several weeks, with no change, is it dead, or will it reactivate with moisture?

If there is a significant risk of it reactivating and damaging the canvas, what are the options? How can it be treated.

I should also mention that I have sold the camper. It was picked up yesterday. The buyer asked about the marks and I told him pretty much what is above. I told him that if it is mould, it seems to be dead. Since it has not changed in 5 weeks of being packed away, I doubt that it will get worse. Anyway, he bought the CT and paid for it.

Today he called to say he took it to a canvas repairer and was told it is mould and it will reactivate. He says the only real solution is to replace the canvas. Sounds like a guy trying to make a sale to me.

I'm not really after advice on the moral issue of whether I have a responsibility for the problem. For the moment, I'm just seeking info on what the risks are and what the possible solution might be.

Anyone out there with real knowledge and experience with this?