Should I express myself to him?

So I had this colleague at my last workplace who I was attracted to. We both were in a difficult team, but somehow unknowingly we used come together for work. We would talk only formally, nothing any casual. I started liking him, but I never expressed it. Then I added him on Instagram. Then after few months we came together for a project and we would talk a lot about work. He was being so sweet. There was another girl in the team but his behaviour was different towards me than me. For me his behaviour was sweet. Then I tried to give some hints like replying to his stories on instagram once or twice but I noticed that he was not opening much and tried to keep minimal conversation. Then I stopped doing anything in about him. Then he left the organisation. I just gave him best wishes on the last day. Then I also left the organization we didn’t have any conversation for 3 months then it was his birthday, he posted something related to it so I wished him on Instagram, again any conversation didn’t happen. I completely gave up on him and focused on my things.

Now we had a big festival 4-5 days ago and out of nowhere he wished me on Instagram literally after 6 months he messaged me. I also wished him. Then he started the conversation ahead. And now the way he is talking is completely different from the way he would talk earlier. Being too open. Trying to keep the conversation going. Using a lot of emojis in the messages:p
Should I express myself?
Should I express myself to him?
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