Thank you for all your comments so far, you all are a wealth of info.
I did not change
solution during the tan, so I don't think there was any sputtering or leaking from the spray gun.
I think that the idea that maybe she touched the tent is definitely possible. I never thought of that, but she could have just touched it slightly if she put her hands out too far. That is a thought.
I have definitely learned my lesson because from now on, no matter what people want, I will do what I know is good. One time over the hands and that is it :).
I just had someone two days ago ask for her feet again and I refused and guess what, it turned out perfect, so definitely will go with what I know works. :)