It’s most likely a clear coat thing
Most 7vs don’t yellow over time but there’s clearly some variation in color over the years and I’d imagine the paint has changed here and there over time, batch specific things etc. there’s a pretty noticeable difference between my 2010 7v and 2015 7v.
Either the headstock wasn’t the same paint/clear whatever or the body is the only part that was subjected to enough UV to yellow it.
looks cool! Enjoy