Same story for me too, upgraded to 3.8.1 and it stopped to charge shipping expenses.
I did some tests, like sending money to myself through a different account and see what would happen, i've found that checking "Authorization/Manual capture (payment shipping)" would partially solve the shipping expenses charging problems, at least for those who have a paypal account. Those who don't have a paypal account but just fill in their credit card details aren't charged with shipping fee any way.
Tried to contact the developer on 24th November but after a couple of mails i didn't get any reply back...