There’s been a change in how Themes are implemented.
New themes issues - Megathread
Right now, this shouldn’t be any major issue but some users might experience changes in print margins, especially if using a Custom Theme.
Usually though, it nothing that can’t be fixed using print margin settings in your print dialogue.
Also, it’s good know that old liquid themes are going to be phased out at one point, so if you are using a Custom Theme, it’s recommended that you rewrite those using either Theme Enhancer feature, or using Themes without any liquid code.