Lettuce Seedlings (Lollo Bionda lettuce)

Hi, I’d like to know if these lollo bionda lettuce seedlings are supposed to be this small after 2 weeks and 4 days from sowing. They don’t look leggy, but it seems like they’re taking a bit of time to develop their true leaves. I’m using cocopeat as the growing medium and plain tap water, under 50-watt grow lights.