Positioning and using a prompt / instruction / error line?

I'm working on a complex GUI where new users are common and so there is a line that either gives instructions, prompts you with information after you select a button that causes a reaction, or prompts you about errors. Prior to me (a UI Designer) the prompt line was at the very bottom of the screen and our users commonly didn't know it existed. On my recommendation we moved it to the top of the page, just below the page title. Due to the occasionally short length of the prompt I chose to center the text so that it would flow from page title to prompt line to page content. I am however getting pushback that the prompt line should be left aligned. My concern for that is if it is a short prompt, it will be to the far left and not be noticed. Could I get your thoughts?