Yes, uneven planchets occurred with some frequency in pre-Civil War coinage and even into the later 1800s. Quality control wasnt always top priority back then so you will frequently see things like planchet and die flaws.
As far as grading goes, your quarter would probably make VG-8 if the planchet was normal. Since it is uneven, I went down to G-6, a slight downgrade. Some would go down to G-4 on it.
I will generally give a smaller downgrade to a planchet flaw (uneven, lamination, etc) than I would to a ding or a scratch since that is considered actual damage whereas a planchet flaw is just an inherent defect.