Should I worry that my bachelor's degree will be revoked because I only completed half my internship hours?
You shouldn't worry about it. The general principal is that the dean of the college that signed your diploma felt you had met the requirements. It would be unusual to second guess that decision years after the fact without a compelling reason (like new evidence of fraud). 

We've had a lot of questions about degree revocation recently. Everyone agrees that this is extremely rare, and almost non-existent when the student acted in good faith and the university deliberately issued the degree. It is difficult to imagine a mechanism where the university would even notice the discrepancy, much less care enough to pursue the matter. 

By the way, I recently gave the opposite advice to a similar question. But the situations are a little different--in the other case, there was a question about whether the degree had been awarded, and why it was awarded. Your degree was issued according to the normal process.