Hall was diagnosed last September with prostate cancer and had his prostate removed in November.
The previous PSA test showed undetectable amounts, but this latest one showed the level had risen.
"[Thursday] I got the phone call from the doctor 10 minutes before first pitch," Hall said. "He told me that my PSA number went up, which is never a good sign after you've had prostate surgery. It means there could be some cells there that could require further treatment, likely radiation. So we'll wait three months and take the test again."
Hall went public with his battle last year in hopes of increasing awareness for testing. He posted an update on his Facebook page and sent out a message on Twitter to update fans on his latest test.
"I shared it to encourage others to get tested," Hall said. "I'm not worried, we'll handle it. It may be nothing, but the likelihood of some kind of future treatment is more likely than not. We'll continue to monitor it, but again it gives me a chance to remind men of all ages to get tested."