There are users out there whom will try to occupy your upload slots for as long as possible (if you share a lot of files.) This has been a known approach/strategy of anti file-sharing companies. So I am always suspicious when I see similar behaviour. I've seen obvious such behaviour from hosts from a number of countries.

If you are 'super' suspicious of their behaviour, give them a temporary ban. But remember to remove that ban at end of session or a day or two later. I keep a notecard open to note any addresses I should remove later on. And yes I do see similar behaviour from same hosts later on. If it happens too often then I give them a more permanent ban.

I would be interested in knowing their host address if you could forward it to me. Firewall console will usually list it.