Bought this 2006 P-Bass used about 18 months ago, it had round wound strings and I replaced them recently with flats and noticed this wear pattern. At first I thought the E string groove had split but upon closer inspection realized it was a collapse of the groove edges into the groove. It gives the vibe of soft nut material, therefore. Also may be a sign of previous nut replacement? Can anybody chime in here with a good assessment and recommendation for repairs if needed? FWIW I noticed some difficulty in setting up the intonation on E as well as slightly distorted sound on the string in question. Bass is the model in this link: Fender American 60th Anniversary Precision Bass 2005/2006 Transparent Butterscotch | As The Crow Flies | Reverb Thanks!