I'd say they look fine, nothing to worry about so early on. Night temperature is a bit cool and may cause stunted growth. You can use anything that will give a greenhouse effect to bring up the temps over night. Also, at this stage and up until around 4 weeks, you don't need to be feeding your plants any nutrients, this can also stunt them giving them too much, too soon. Your growing medium has the sufficient amount of nutrients in it already, so feeding it so young could end up being overfed and then nutrient burn, root lockout etc. So only feed when it tells you too, with early deficiency signs and this is way to early to tell. Hope this helps.
