I think this is an hypoxic buzz, as long as you don't lose control over your body (like shaking) it is not a samba.
I sometimes get those also though I find it hard to predict when I will get one (as I'm doing recreational freediving). Not always the longest/deepest/most excerting dive will produce one for me. I think the speed of the ascent in the last 10 meters is a factor - getting O2 sucked back into the lungs from the blood (common reason for SWB).
I considered that as a normal part of freediving and never considered them as a risk. I always feel in full control when I get them. Now that you brought this topic I'm curious as to how common and risky those are.
Good question.
