You see the secret mark, so you are correct that the plate was made by Continental. However, I cannot tell from your picture whether the paper is hard or soft. When American took over the facilities at Continental, Cont was already using a softer grade of paper than they had been using earlier. Under American they kept using the softer paper and the plates with Continental imprint until replacement was necessary. So, if hard paper, it's Continental, but if soft it could be Continental or American.
Here is a set of similar imprint captures on soft paper for the 2c vermilion. Same concept: