I don't know how your resume is written; if you use the words "job title" in there for each job but his change doesn't sound significant enough to me to worry over, either way. I'm sure you know the differences between a "financial analyst" and "controller" but I doubt most readers of your resume do, or care much, unless they've been told to look for "controller" or are so small as to scan for just that title, in which case I wouldn't want that job. Presumably you described your duties and an astute reader would realize it's all-but-in-name-controller!