My guess is that Johns fathers name was Henrik Henriksson (if he was Swedish, but it is a proper guess) if anything as Henderson isn't really a Swedish name, Henry is however used. Or are you saying that they went to Sweden and came back?
Try to post a question on the Swedish forum http://aforum.genealogi.se/discus/
click on the left hand side menu reading "Ämnen" and you'll find a section called "Discussions in English". You will have to register in order to post a question but it is free of charge. People there are great and really keen to help out