what kind of fertilizer are you using? it seems to not be working and remember to go with about 1/4 strength about maybe once a week until they get bigger. This is the perfect example of how my plants look after 2 weeks and mine tend to stay that small in seedling mixes unless i give em some nutes. Also, dont let people tell you that the plants have enough food or power or whatever they say to get you to 4 nodes because i have had a few people tell me that on the boards and i find it to be complete bs in my experiences they get stuck at a 100% stand still. so i guess my answer is i dont think your plants have outgrown the pot but if you have been giving them ferts with no results which is really wierd then the plants can use a transplant into something a little more nutrient rich.