Yeah, they're definitely stretching -- how far away is your light? I don't have any hands-on experience with LEDs but I think they're supposed to be around 18". Depending on your light it could be closer or further, you need to experiment since LED fixtures vary greatly from maker to maker. Try moving it 6" closer to the plants (or more if it's really far away). You don't want to burn them but they stretch like that when they're not getting enough light.
When they get bigger and you transplant them, you can bury some of the stem to help correct it.