Kija

I want to pursue a PHD in economics, however, I received a grade of A- in my first two college math courses (advanced calc and multivariable calc) I am planning on taking linear next semester, but multi kind of kicked my butt (my class had a very difficult professor, and many of my classmates said linear was easier for them to understand than multi due to this). I go to a top 5 liberal arts school and am in my sophomore year. I get A's in all my econ courses and have some research lined up for next semester and a TA position, but I am still very worried that these two A-s may indicate that I am not good enough at math for econ grad school. Am I right to be worried?