Yeah, I would try that. Sounds like a glitch in the radio. If that doesn't work try putting the radio into test mode.
Summarized from the Ford Service Manual:
Speaker Walk-Around Test:
NOTE: To enter the speaker walk-around test or audio unit self-diagnostic mode, the audio unit must be turned on and in radio tuner mode (AM/FM).
1. To enter the speaker walk-around test, simultaneously press and hold the audio unit preset buttons 3 and 6 for approximately 3 seconds, then release.
2. The speaker walk-around test applies sound to each speaker for about 1.5 seconds. Each speaker is tested and displayed on the audio unit in the following sequence: RF, LF, LR, RR.
Audio Unit Self-Diagnostic Mode:
• NOTE: Always document and clear DTCs and carry out the audio unit on-demand self-test again.
1. To enter the following tests, press the desired preset button while in the speaker walk-around test or while in the audio unit self-diagnostic mode.
2. To exit the audio unit self-diagnostic mode, turn the key or the audio unit to OFF.
3. The audio unit self-diagnostic mode has 5 tests available:
• Preset Button 1 = Audio internal/external SELF TEST. This test is an on-demand self-test. If SELF FAIL is displayed, press TUNE > to scroll through the DTCs stored. Refer to the Audio Unit DTC Index. If the system is OK, SELF PASS will be displayed.
• Preset Button 2 = View/Clear continuous DTCs. NO DTCS is displayed if no DTCs are retrieved. If DTCS FOUND is displayed, press TUNE > to view the DTCs retrieved. Refer to the Audio Unit Diagnostic Trouble Code (DTC) Index. To clear all DTCs, press the EJECT button. DTCS CLEAR will be displayed.
• Preset Button 3 = SIGNAL TEST. This test measures the average strength at the current tuner setting. ** Perfect for testing antenna types and position changes. **
• Preset Button 4 = Software level query. This test queries each audio system controller for its software configuration level. SOFT LEVELS will be displayed upon completion of the query. Press TUNE > to scroll view the software configuration version level.
• Preset Button 5 = DISPLAY TEST. This test will light all the audio unit display segments for 5 seconds. When the test is complete, DISPLAY TEST is displayed on the bezel.
5. To exit the self-diagnostic mode, press the power button on the audio unit or turn the key to the OFF position.
Audio Unit DTC Index:
DTC - Description - Action
B1317 - Battery Voltage High - CHECK the charging system.
B1318 - Battery Voltage Low - CHECK the charging system.
B1342 - ECU Is Faulted - CLEAR the DTC. CARRY OUT the self-test. If DTC B1342 is retrieved again, REMOVE the audio unit and SEND it to an authorized audio system repair facility.
B2406 - Audio Disc CD Player Internal Fault - CLEAR the DTC. CARRY OUT the self-test. If DTC
B2406 is retrieved again, REMOVE the audio unit and SEND it to an authorized audio system repair facility.
B2477 - ECU Configuration Failure - CLEAR the DTC. CARRY OUT the self-test. If DTC B2477 is retrieved again, REMOVE the audio unit and SEND it to an authorized audio system repair facility. REFER to Section 415-01 . TEST the system for normal operation.
B2924 Audio Button Stuck INSPECT the audio unit for a stuck button and REPAIR the concern, if possible. CLEAR the DTC. CARRY OUT the self-test. If DTC B2924 is retrieved again, REMOVE the audio unit and SEND it to an authorized audio system repair facility.
B2965 - Audio System Speaker Circuit Fault - See Ford Factory Service Manual for troubleshooting steps