Again, am I irrational for wanting a heads up, or a check-in?
No. That is common courtesy. If it was my partner coming home that late - in the middle of the night, no less - I'd be worried sick and would absolutely call or text or both.
My partner is not a recovering A and I get the "his recovery is his recovery", but even so, IMO it is not unreasonable to expect him to let you know he'll be *that* late.
Having said that, I've never been in the situation of living with a recovering A. I left mine, still very much unrecovered, long ago. So I may not have the right insight on this.