I don't suppose the OP will see this after eleven years, but this site has info about picks:

https://banjonews.com/2009-08/maintaining_strings_and_picks.html

He says that picks get softer from a warm environment or the warmth from fingers. I suspect that what the OP had was a warm, transparent Dunlop pick.

When I want a soft sound, I use a Herco pick.