I had a pretty disturbing interaction on this trip at the Immigration in Wuhan. I lived in China off and on for a few years. I have been in and out of the country 15 times total. It is pretty much just like any other country, no issues. At times maybe ask a question but rare. This time, I was asked why I am going into China, who I am meeting or going with, how many days. address of hotels, they saw me with my friend ( she was already waiting for me on the other side ) they asked my relation with her. Asked how I knew how and if she is with me. I suspect it was probably because i am much older than her and she looks young. She is 29 and I am 50. They have to make sure there is nothing going on or possibly something else. I told them we have been traveling together for 7 years and our passports match for all the vacations we have been on. As soon as i said that, they didn't ask anything else. Then he said for me to obey all Chinese laws and gave me a little slip in my passport that said that as well. They called someone over and kept looking at my passport and the picture and asked what I was doing in Vietnam etc etc. I was there for a total of 13 minutes about 11 minutes too long. It was very concerning but in the end everything was ok.