I kindly disagree. If you check out http://www.jbrains.ca/permalink/the-four-elements-of-simple-design 
the cost is not marginal at all. Anything that makes things more difficult to understand comes at a cost. One is that it will make it harder for collaborators to help. If a piece of code is simpler, is easy to understand, does not have duplication, I can see no reason why one MUST follow this practise. You haven't mentioned any advantage in the concrete case of doing this other than that it's a good practise.

For now I will move them all to the top of the source files as it's your project, but please reconsider.