The reason is how much the D and G strings are "bent" between the nut and the tuning peg. They catch and then suddenly let go. Les Pauls are notorious for it.
If you are brave, the fix is taking some really really fine sand paper (1000 grit), wrapping it around your string. and sanding out the divot in the nut where the string goes. focus on the area opposite the fretboard. (I have never done this myself as I find I can only play Fender necks very comforatbly.)