i'm not familiar with this strain so i don't know if this could be a strain-related problem...

anyways, put a little fan on them to strengthen their stems, and check the base of the stem to make sure it's not all brown and mushy. if it is, it's stem rot and your plant is doomed. this is caused by overwatering tho, so if you're not overwatering don't worry about it. it's just something to look out for. so use a fan, and if they lean so much that they fall over- prop them up with a bobby pin or something.

they look really great other than the slight lean tho!!!