I understand that you are talking about the experience you have (what you saw and what you feel).
The reason that I asked those question was I hope to be able to find more information.
If you saw "rainbow pattern" at the same location as you walk through. It means that there is a some kind of screen so that light can be reflected back to your eye.
We see object because light reflected from surface of the object and enter our eye (unless object is a light source).
Because the "rainbow pattern" you saw is not a light source, so it must be some kind of "screen" to be able to reflect light.
And I have not figure out why/how the rainbow pattern was formed from your information.
I hope someone else can provide a better explanation.
In case you see the same "rainbow" again, please remember to take some picture.
I believe it will help if we can see those picture!