Probably. In the parlance of the Common European Framework of Reference for Languages, proficient would be a C1; 4 years of HS Spanish would at most be B1/B2. The vast majority of students who scored a 5 on the AP Spanish exam would not be considered proficient. Now, if you speak Spanish at home, the answer might be different.
https://en.wikipedia.org/wiki/Common_European_Framework_of_Reference_for_Languages