Take the clear lens off while the ignition is turned to on and bump it with your finger and see what happens. Very likely you pushed the needle down a little and it is getting caught on the gauge face itself.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.