Greetings Susan
That certainly Does seem to have been an OBE. The vibrations and floating down the stairs are both common phenomena associated with OBEs. The floor color could have been due to 'reality fluctuations'. This is a term (coined by Robert Bruce) denoting minor differences between the astral/ethereal Real Time Zone (RTZ) and its correspondent physical location. This fluctuations are usually quite minor. I have noticed them during a few of my projections.
Congrats on getting the card experiment correct. It has been done a few times by others but getting the right card is actually quite rare.

Regards
Grey