Yeah, rootbound for sure.
Here are the signs of a rootbound plant to keep in mind in the future. It happens to the best of us. And it's happened to me in the past too.
- The pot has been filled with roots and there is very little soil left 

- Because there is very little soil left when you water, it goes right through and drains out, nothing is retained 

- The plant wilts within a day or two of watering, because with very little soil, no moisture is retained

- The roots are growing out of the drainage holes

- The roots are cracking the pot 

- The plant is top heavy or way too big for the size of the container
To determine the above, sometimes you will need to gently pop the plant out of its container and take a look at the roots.
2. Moving Plant Into Bigger Container
I like to move the plant into a bigger container, because I like to grow my MMJ plants big, but if you are tight on space, you might want to just root prune it, and plant it back into its original container.
1. To repot your plant into a bigger container, choose a new pot that is only about 1 or 2 inches larger in diameter than the old one. You don't want to get too big a container, because the pot will hold more soil and more water than the plant can use, which can lead to rot.
Also make sure to water your plant well a few hours before repotting so it has plenty of moisture to help it withstand loosing some of its roots.
2. Take the plant out of its pot, knock off the old soil, if there is any, and tease out the roots and unwind circling roots and cut off any that look rotted or that need to be pruned back.
If the plant is totally root-bound, make cuts from the top to the bottom of the root ball
3. Put some potting mix into the new pot
4. Center the plant and plant it at a depth of ½ inch from the top of the pot
5. Plant it no deeper than the top of the root ball. If you plant it too deep, it will rot, and too high, it will dry out
6. Tamp the soil down as you work
7. Finish filling in
8. Water it
9. Allow to stand for 30 minutes, and then empty any residue water from the saucer
10. In a few weeks, give it some fertilizer and you're done!