I'm not sure if there's a good way to tell if your plants are root bound in those pots, but if you can get any kind of look at the root ball then you'll know if you need to transplant them or not.
You might throw them into shock if you transplant them while theyre flowering, but if the roots have nowhere to go then you also run the risk of killing it completely. So, probably not a good idea if you dont have to...