i dought it, the rule of thumb is 1 gal pot for every foot of height of plant. eg: mj plant is 3ft tall = 3gal pot (10-12inch pot). only real way to tell is 1 if you see roots coming out drain holes, 2 stunted growth (no other factors, eg: no water, nutes, etc.) 3 remove plant from pot to see if roots completly cover whole dirt ball.
Its pretty easy to check for root bound, just before you water, and the soil is somewhat dry, use a knife and push it down around the edges of the pot in two or three spots. Then turn the pot upside down and remove the plant, it should slide out easily.