Talking specifics... I have "chaffed" before now on the inner thighs on runds over 10 miles, so on that experience, you will probably be ok in that particular "region".
However, I had the unpleasant honour of experiencing nipple rash for the first time about a month ago on my first 20+ mile run, which struck at about mile 18. On that evidence, I would think there is still a risk.
My perspective is that given you're only rubbing it on the outside, it can't have any adverse effect, so give it a bit of the old 'enry coopah - "splash it all over!!!"