I also did a kind of patch test revealing that I have some sensibilities to some things, like everyone, in fact.
It had shown that I do very little reaction notably about an element in clothes, or in flagrances.
Well I am not a nudist and wear clothes everyday without any reaction, neither had inflammation when I put deodorant so it wasn't concrete at all and irrelevant with lips.
Plus, it is difficult to test THE factor which will reveal that it would be the cause.
Also, if we were very allergic to something, I wonder how it would be just localized in our lips, without inflammation in mouth, neither tingles or something else, concerning food allergies for example.