Change in the way these two dogs play together?

A few months back Dexter enjoyed several play sessions at our local park with a young GSD - Max.

At the time Max was seven months, and Dex was about 16 months. They played together so nicely, on several occasions over about a month.

Then Max's family went away for a while and so we didn't see them. This week they returned and we met up with them at the park.

Max now 11 months and huge; I would never have known it was the same dog had I not known his owners to say hi to. He's stunning. Dex is now 2 and also somewhat bigger, as he's filled out a lot.

He and Dex were both off leash and greeted one another. Within minutes, Max kept trying to put his head and neck over Dex's head/back. Now normally Dex is delighted to play including very rough play. But when Max did this, Dex's hackles came right up and he actually growled at Max.

Max's owner remarked that Dexter was 'unsure' about Max and we separated them, at her suggestion.

Does it sound as though these two will not be able to play together again...? Or should we NOT have separated them??

I would have (wrongly???) let them interact for a while longer, while remaining close by to monitor.

Just wondered what folk think?

For some dogs putting their heads like this is a sign they are trying to dominate the other dog, & Dex was responding to this.Max is just at the puberty stage & trying things on. You could have left them a little longer for them to settle their pecking order but you'd have to be able to stop them if it escalates.