Oh, absolutely! That is a key part of being a scientist. Granted, sometimes your ego might get a little bruised but the essence of science is to seek the truth. And the truth is found by building evidence. If someone can present evidence that contradicts your understanding, you must be open to considering it. That doesn't mean you have to just accept it every time someone challenges you, but you should be open to debate and to evolving your understanding. New observations, better mathematical models, faster computers, fresh ideas, all kinds of things can help to change the understanding of an idea and as scientists its our job to be open to changing our minds.