Firstly can I apologise if this sounds stupid but I have MH issues and sometimes don't know if something is 'normal' or not 
Quick back story; I have been with DP for a few years now but because of my issues we don't live together and only see each other once a month (sort of date night) although we talk every day and might meet up for coffee etc. He's happy enough with this but I think he would secretly like to have more as he sometimes mentions living together etc but he knows my background and is content to let me set the ground rules.
I have to travel now and again with my job and I've just been told I have to go to another part of the country for a couple of days which will involve an overnight hotel stay. When I told DP he joked about 'sneakily' travelling too and booking in to the same hotel. I thought he was joking so just laughed it off. However a couple of hours later he texted me saying he was serious. It immediately made me uncomfortable and I told him I would be working but he said he could see the city during the day by himself and meet up with me at night in the hotel. He also said to tell my manager about it
He obviously realised I wasn't too happy with it because a couple of hours later he said it was a stupid idea and just to forget it.
Aibu or is this a normal thing? I'll be working so i want it to be as professional as possible but maybe it's what people do. A bit of help making sense of this please.