Dog Play : How to Read the Situation?

My 7-months old Pembroke Welsh Corgi had a play with this Huksy in a dog cafe. Overall, my gut feeling tells me they are having a great time - though I can’t articulate exactly why (maybe because my Corgi kept going back for more even after he’s unpinned). Some bystanders seemed slightly worried so I thought I should double check my judgment. Are there any signs that I’ve missed or I should look out for?