I have found that lately (and I'm not sure why), that my thumb is sore from pressing too hard on the back of the neck. I've never needed to press hard and hadn't had an issue before so I definitely think this is a subconscious thing for some reason. When I play my Sklar, I tend to wrap my thumb (I've heard it is not good to do that and I've heard - who cares - do what you need to) around the neck, so it hasn't really been an issue there. I've been leaving my Sklar out on the stand to play at home so I have been playing it more. Maybe I'm just getting used to the thinner neck? I usually play my ABs for actual sets and that is where I am doing it.
Any tips? I'm guessing the main answer will be "practice not doing that".