First time to have felt something. What is it?

So I’ve used the Aneros for about a handful number of times, and haven’t really been experiencing much other than some light sensations in the butt when I try to make some really concentrated contractions.
Due to lack of privacy, I haven’t been able to have a session in a month or two. But 2 nights ago, the opportunity for a session arose, it was bedtime and I was relaxed, I decided to give it another shot.

I had no expectations this time, and just laid still, relaxed, and tried not to think about anything. 20 minutes in, I decided to turn the lights off and try to go to bed with it inserted to see what happens. (I couldn't fall asleep of course)

50 minutes in, I started to feel something I’ve never felt before for the very first time, it was a light tingly sensation in the legs/pelvic region, a little similar to like when your legs are numb from sitting on it. Then I feel a subtle warm wave flush through my body, it spread from from my legs up to my chest, and my arms, my heartbeat begins to race and pounded heavily. I didn’t dare move in fear of losing this feeling. As my heartbeat pounded on, I started breathing heavier too. It wasn’t an intense or a really pleasurable feeling, nothing like an orgasm at all, but it was very nice. After 10-20 seconds the feeling subsided. My penis was soft throughout the entire session.

I felt like I was finally making progress!

After that, I went on for another 2 hours, but could not repeat the same sensations other than some light tingling in the legs, so I took it out and tried to fall asleep.

Last night, as I was trying to sleep (no Aneros this time), I decided to relax in the same way, and lay completely still as I did the night before. After a certain amount of time, the same feeling took over! My heartbeat was racing, and I felt the same hot rush gradually flood through my body, although it was not as intense as it was the night before.

That same night, the tingling in the legs occurred more frequently, and since I had no aneros in, nor feeling any particularly strong sensation, I decide to try to move them this time when I was getting that tingly numb sensation, and felt some semi-involuntary spasm/shaking in them.

Is this what people call a p-wave? Or is it something else? Love to hear more from others who have gone through the same phase or have had similar sensations!