Same here. I've only had this condition for about 6 months, and I'm 100% sure it was only on my lower lip. I left it alone based on some suggestions here and I noticed I finally got the dreaded triangle in the middle of the upper lip and some tiny flakes that divide into squares and now the affected area on the upper also gets white too.
Although I'm not really sure if it was because I left it alone or it was coincidentally about to get worse during that timeframe.