yea, but trust me when I tell you, they will
take off.
Especially once flowering starts, the plant will go through a 'flowering stretch'.
Here's an example, because this plant wasn't even 10" tall, and then it started flowering, and as of earlier, is 17".

now, you're plants are 21 days from the day they broke the soil and poked out tiny little seed leaves, no?
you do look rather stunted for 21 days, but, you transplanted them so that doesnt necessarily surprise me, lol.
Next thing you're bound to get asked, is what is your pH?
cause having the proper pH at the root zone is
critical to your plants health. In soil, the plants like a pH of somewhere between 5.8 and 6.5, but most people go with 6.5...anything higher or lower than those two numbers there, and you're starving your plants of the nutrients it needs to grow and thrive.