It's not selfish at all. I treat other people the same way. I am eager to help teammates with their problems and frequently do. If they have a question they can send me an IM or email and I will respond when I have time to answer. Interrupting other people to solve your problems is selfish.

If you need clarification then send an email, add a comment in your issue tracker or set up a meeting. There's no reason to interrupt someone doing productive work to get clarification on a story. You should be able to manage parallel stories and make progress as you get clarification.