Confused by my dog's reactivity progress

I have a 5yo husky x GSD who's always been a frustrated greeter. He's not human reactive. He basically just want to meet other dogs and play. It was pretty intense when he was 6mo to about 2yo. This past year he both became much better..and worse in other areas:

- I can now pass dogs and he'll have zero reaction, aside from a quick glance and maybe a sniff from afar.

- Sometimes he still pulls and jump like a maniac to meet a dog, but recovers within 30 seconds of passing the dog, but these interaction are becoming rarer.

Where he got worse...

In the past 3 months he's barked and growled at dogs on 3 different occasions. My dog isn't a barker (aside from alert barking) and it was legitimately the first time in my life that I heard him bark. First time, passed a dog pretty close on my building's lawn (about a driveway width apart), second time the elevator opened to a couple with a dog, they didn't get in because it would be to hectic, but by the time the doors closed, my dog barked and growled. Third time, this morning on a walk the other dog was on the other side of the street, reactive himself, pulling a growling, mine started barking too.

I'm not sure if this is concerning or not....