Something related happens with me every once in a while when someone makes a statement of the form A -> B and I say 'yes' or 'ok' in response. By saying 'ok' all I am doing is to acknowledge the truth of the statement A -> B, however, in most cases, the person assumes that I am agreeing that A is true and hence ends up concluding that B is true as well.

One example is this -

I go to a stationery shop and ask for an envelope. The storekeeper hands me one and I start inspecting it. The storekeeper observes this and remarks, "If you want a bigger envelope, I can give you one." I say, "Alright." He hands me a bigger envelope.