Behavior change

My boyfriend of about 4 years goes on the same trip every summer to see family. He has done this for probably 25 years. The last few years, I went with him. This year, he went kind of last minute and I wasn't able to go due to work. Before he left, he told me to get specific dates off in a month so I can go with him there. We both love the area and always have a blast. To my knowledge this has been a once a year trip for him, he had never gone twice in one year. Also, he has been weird but in a good way. He has been saying "we" more and talking more long term plans type things. We are both older and have both been married before. When we met we both discussed what we wanted and it was not marriage, it was companionship. We both seem to be very content with how the relationship is working, we don't live together and we get along very well. We haven't even discussed marriage. My friends seem to think he is going to propose on this trip. I'm not so sure. I'll be good either way but I don't have another explanation for why he's suddenly acting so different.