Weird stretching that I can't explain

I am running a 315W CMH light in a 3x3 tent. All three plants are Blue Dream Autos from ILGM. They started out slow, but have been stretching like crazy. I had the light at around 2ft to avoid heat burn. Now I can't go any higher and they are getting too close. They are finishing week 5.
A bit at a loss short of starting over. Not sure how much more they will grow.

Looks almost like they sent you photos. I'm seeing preflowers but with the autos I grew they were starting to stack by day 35

Raised the tent by making a box frame under it. Got plenty of room now. Well it least another 2ft. But the stretching seemed to have come to a halt.
Pruned a bit and run some strings for support. Do the preflowers look good, or too sparse?