Minor but persistent saddle sore - Safe to continue riding?
I'd perhaps look at your saddle again.  Padding isn't everything and there is a lot to be said for fit/sit bone width.  Consider getting measured/fitted.  I know what width fits me in the brand I buy.  Personally, I think every serious cyclist should know their saddle size as well as their frame sizing.  Keep in mind that all your riding up to this point (before saddle change) developed extra padding/tissue/internal callus (whichever) on the contact points of your old saddle.  Moving those contact points just a slight bit by getting a new saddle can make quite a bit of difference.    

Not to be rude, but what is your hygiene like?  I would recommend making sure to always wash after a ride (commutes included).  Always ride in clean shorts.  Toward that goal, if you haven't cleaned/showered/bathed recently and go for a ride, you really aren't riding in clean shorts (your skin isn't clean, even though the shorts are).  Consider washing before and after a ride.  Are you using a chamois cream of some sort?  Part of the problem can be caused just by friction.  A good chamois cream can help.  Some have various antibacterial/anti-infective "stuff" rolled in and can help on multiple fronts.  

If you are going to look for less padding in your seat, you may look for more in your shorts.  Seven hours for most folks goes past stage type training and into endurance riding/training.  Ultra light sometimes gets sacrificed for comfort.  You may look for touring or thicker winter padded shorts/bibs and opt away from ultra light race padded shorts/bibs.

I have done a fair amount of winter endurance riding (100 miles on snow) and sometimes you just forget your prep and end up with a sore.  I've lanced my own in the past to speed healing, but that's not for everyone.  Once you have one (I have my own set and recurring spots), it's kind of always a preventative fight while you are trying to train.  In the end, if all your equipment is properly fitted, proper hygiene and prep (wash before/after, clean shorts and chamois cream) just become a regular part of your training like bike maintenance and proper nutrition.