Q.bolting lettuce starts
I bought leaf lettuce starts and planted them a couple weeks ago. They didn’t grow much more than what they were when I bought them and now they are beginning to bolt. Temperatures have not been hot yet.

This article will help you:
https://www.gardeningknowhow.com/edible/vegetables/lettuce/bolting-lettuce-plants.htm
A plant "bolts" when it is under stress. It is caused by high temperatures, long periods of high light intensities, and drought. Could this possibly be water stress (under-watered)? How were you watering your lettuce?