IMHO if the crew had to do anything out of the normal then they should tell the passengers why they did as soon as possible. This applies to things that have happened and what is going to happen. You have a load of people behind you in a metal box who generally speaking, have no idea how and what is holding them up in the air. The only two things they can put their trust in are the two pilots up front. It is only fair that they should know what the pilots had to do and why should something happen out of the ordinary.
At the end of the day their employers pays the crews wages.