Usually your plants will go AWAY from the heat source.....not toward it. What kind of light do you have going and how close is it? The temps themselves are not bad.......but if your light is too close it will increase the heat around the seedlings. And do you have a fan or some sort of ventilation going for them? They should definitely have that as well.

I'm no soil pro....hence the link to problems for soil growers....to me the issue seems to be either ph or too much nutes for seedlings. It just doesn't LOOK like a heat issue....but then seedlings can do funny things. Also....which three are we talking about.......the three closest to the light? If its heat you should see it in a clear pattern from the closest plants outward.

I'm afraid that is all I can offer you here so feel free to take my advice with a grain of salt.....as I said soil is NOT my strong point.....at all.