It's not root bound if it was just transplanted 3 weeks ago. Could be related to the way you water. Looking at the soil you are using it might also be a soil and pot that doesn't have good drainage keeping the lower section of the soil too wet.
It doesn't seem unhealthy. Repotting it into a bigger, plastic container will eventually just give you more roots and a bigger plant. You could try a cloth grow bag or one of those air pruning pots....
It doesn't seem unhealthy. Repotting it into a bigger, plastic container will eventually just give you more roots and a bigger plant. You could try a cloth grow bag or one of those air pruning pots....