I believe the plants do this when there is too much light/heat for them to cope with, so they lift their leaves like that on an angle to reduce the surface area of where direct light is hitting the leaves. I have had this occur on very hot days (35+ Celsius) outdoors and I also think it is a "strategy" used by the plants to lessen transpiration/water loss from too much heat also. The fact it is mainly occurring with the leaves that are closest to the light would suggest my idea about too much light/heat has some merit to it. Try raising your light a bit or changing the air flow in your tent to see if that changes your plants behaviour, making sure the main air flow is between the top of your plant and the bottom of your light(s). I do not think it is doing any damage, but it is causing some distress to your plant. Hope this helps,.... Organoman.