| If it is happening on the E as well, my first guess would be that the end of the 9th fret needs to be re-seated or that individual fret may need to be leveled. For a rough gauge, take a credit card or other straight edge that will span only 3 frets (8, 9 10) and see if the card rocks on the 9th fret. If it rocks, look for a gap under that one. Either way, I would take it to a tech- it would take less than 30 minutes to re-seat or level, crown & polish that one fret. | 
