My first ever(professional) reiki experience

In short it was relaxing, it was interesting, and it was "spacey".

Detailed description
The Reiki session was held in a spa room. I comfortably settled onto a nice bed, laying on my back, and I was told to relax myself and be open to any experience I would have and also be open to let the ki or chi or prana do its work. Eileen started out with placing her hand gently on my chest and then going on to behind my neck, my forehead, my scalp, then moving down to the shoulder and chest again. Each hand placement was initially made for a minute or two. Thus far, I was just relaxed and didn't feel any sensations or heat that are usually said to accompany a Reiki experience.
She then moved her hand to my chest and placed it there for a prolonged period.. I started feeling heat on my chest and felt 'lightness' in the chest.
I asked her if she still had her hand on my chest, for I was not sure, even though I 'felt' pressure, as though from a hand. Just as I asked this question, I felt her two hands on my feet. Wow, so her two hands were on my feet, and I was feeling pressure on my chest, just as if there was a hand placed there. This was amazing. The pressure stayed for a while. Periodically, I was reminded to take deep breaths and allow the chi to work through.
I was then asked to flip over and Eileen worked her hands on my back and did I feel some heat there or what. I wasn't imagining it for sure, it was searing out there, though in a sort of bearable way. Eileen worked on the back of my neck, my hands. I remember her pressing my hand hard and the pressure stayed (similar to the chest), even though she went to work on my legs.
So this was again the case where, there was pressure applied onto my legs from her two hands and then there was the 'phantom hand' (sure did feel like that) applying pressure on my wrist.

At this point, I started feeling spaced out. I was feeling a little disoriented and the eastern instrumental music in the background seemed to be aiding this 'spacey' feeling. I was kind of scared, and mentioned this to Eileen. She suggested that I imagine myself grounding my body to the earth. I did that visualization and in a few minutes, I felt less dis-oriented. This dis-orientation is really new to me. I have felt this feeling once before, when I was undergoing a lot of changes in my life. And as before, it felt frightening and weird.

The reiki master mentioned that she had seen very few clients getting 'spacey' on their first reiki session. Hmm, I have been meditating regularly, the past three months, and that might have contributed to my current experience. So, after exchanging some more ideas, and having my questions answered (a lot of them), I left the place feeling a little 'spacey' but oriented back to the so-called 'real' world.

Principles:
So from what I understand, the philosophy behind Reiki is that: The 'chi' (china) or 'Ki' (Japan) or 'Prana' (India) or the life force is a universal energy that can supposedly be tapped by anyone if required. Reiki is one such way of tapping into this 'ki'. The patient's or client's body is considered intelligent and wherever there is a need, the body directs the flow of the Ki through the Reiki Master's hands to the affected part of the body. So, in accordance with this understanding, Eileen let me know that I needed the energy most on my back and shoulders and hence I felt the ki there as 'a lot of heat'. This makes sense, since I sometimes carry a laptop along with many books in my backpack and my shoulders and back take a beating when I do that.

I am going to go for some follow-up reiki sessions and see how they go and what I experience.
I am pretty open to energy work and the like. It fits my belief system pretty well (although you don't need a belief system for Reiki, which is a secular practice) .