I don't think anything changed here and I can sort of see what you're talking about, but it doesn't look like that in general to me. I suppose font size manipulation in the browser could cause this.
It looks to be Firefox specific in my tests. I only see a horizontal difference -- vertical is generally fine by default. The horizontal difference appears to just be a 1 pixel difference or some sort of rounding thing within the browser that exaggerates the issue.
I don't think there's a ton to change with this to be honest, at least not at this point.