I work in a store that has a large copy and print centre. I know that the EU has just brought in some new stuff to do with copyright and my staff can be fined as well as the company etc.
I've also heard that there's a lot of grey areas concerning copyright. First the copyright owner has to see you using the work.
I heard the same thing about them just telling you to take it down but I think you can have such a thing were they can take you to court if they have had loss of earnings or feel that you have damaged their reputation.
I agree with FlightKid
I think the best thing to do is confirm it with them via email at least so you have something in writing think of it the other way if it was your work. It's just polite.
To copyright work you also don't need to spend mega bucks I was told the easiest way is to send the copyright work in a envelope to yourself, don't open it, in the case that you need to take anyone to court over it you have a dated sealed envelope to produce proving when you did the design. Just thought I'd throw that one in.