Yes, I've definitely gotten better at basic physics as I've gotten into more advanced material for my physics major. Maybe that's because advanced physics really just builds on the fundamental principles. It seems to me that all of the physics you'll ever learn, you learn in your first two years. There's really no new physics in advanced classical mechanics or statistical mechanics, just more mathematically advanced techniques. So I guess you're bound to master projectile motion in the process of learning the new stuff.
My experience was quite similar in math. I feel that I have a very in depth understanding of the concepts I learned in the first four semesters of calculus. But strangely enough, this is probably because I didn't take my math major too seriously. To quote my math advisor: "Arun, the reason you're getting good grades in math is because you take weak classes...at this rate you aren't going to get into graduate school." (little did he or I know that I'd end up going to grad school for physics instead of math). While all my peers were taking rigorous analysis and topology, I took advanced calculus, applied linear algebra, and complex analysis. So while all the other math majors were learning about important topics in mathematics, I was basically taking "calculus I for juniors."
Oh, and I also tutored physics and math my last year and a half of college. I'd recommend this to everyone; being forced to explain this stuff to others really gives you a special insight.