Unattended fire - general opinion?

I was recently camping in a state park campground where there is no fire restrictions. On the morning I was leaving, the campers at the neighboring site had left a fire going at thier site. I noticed they were gone when I was finished packing up, car not at the site. The fire pit still was burning with actual flames , not just smoldering.

I waited around a few minutes while finishing packing up, then I approach their campsite, called out to see if anyone was in the tent. Since it was obvious nobody was home and I was about to leave, I took a jug of water on their table next to the fire and put out the fire, using about 2/3 of the gallon.

Was i wrong for invading the space? It must have been at least 45 minutes that the site was vacant. I just felt I couldn't leave the area with a fire going, there were no other campers in that side of campground. Did I overstep boundaries?