Why would an ex unblock me everywhere after 1.5 years of total radio silence?

​Hey guys, looking for some male perspective on this because I’m genuinely baffled.

​My ex and I had a really ugly breakup about 1.5 years ago. Immediately after it happened, we cut all contact. I blocked him on Instagram, and he blocked me back on both Instagram and Facebook. We haven’t spoken a single word to each other since the split.

​The only "contact" I’ve had with his side of things was about a year after the breakup (so, roughly 6 months ago). I dropped off some of his personal belongings at his mom’s office because I knew they were valuable to him and didn't want to just throw them away. I just told her to pass them along to him, and that was it.

​Fast forward to today. I still have him blocked, but I happened to notice recently that he has completely unblocked me everywhere (IG and Facebook).

​If a breakup was that toxic, and it’s been a year and a half of absolute silence, what goes through a guy's head to make him go through the effort of unblocking an ex? Is it just curiosity, a sign of moving on, or something else?

Also.. I should note that my profiles are all locked so he can't really see anything on my profile.

​Would love to hear your thoughts or if any of you have done this before. Thanks!