Thank you for letting me know! Another thing, I've tricked the Don's toll guy into letting me pass without having me pay, but the part where the Don comes after me hasn't triggered. Was there something else I was supposed to do? When I talk to the toll guy he just says "Wait until the Don hears about this!"
UPDATE: I'm assuming it's now a random event rather than one that happens immediately after triggered, because after re-entering the slums a few times I was suddenly approached by the Don's guys who said he wanted to see me.