@Mikeross750 I wouldn't be too worried. I can't comment for other firms, but where you have application questions and cover letters, the general bulk of graduate recruitment's time when sifting through these is to make a decision based off what you have written in those answers, not how you've formatted your work experience. I am sure they know that everyone writes it out a little differently, and unless they've specified the actual order/rules, I would hope they wouldn't place too much emphasis on this.
Personally, I think you've approached it in a way that most actually prefer, so that comment was probably just their personal preference.
I am sure you'll be fine!