Seedling steps

Seed germination is best at around 24 degrees and does not require any artificially enhanced humidity levels, there is plenty of moisture in the jiffies. Remember, moist not wet with your jiffies. At this stage your seeds should be completely fine with no adverse effects what so ever. However, continuing with any excess humidity after they sprout can lead to fungal problems, such as "damping off" which causes death by rotting the stems where the exit the soil. Cannabis is remarkably tolerant of heat, as long as the roots are moist. I grow outdoors in soil, in full sun, right from day one, with Summer (day) temps anywhere between 15 and 45, for 4 months and my plants cope without any problems or hiccups. You will not lose anything because of what you have done. Cannabis is a tough plant, not a dainty orchid which needs to be wrapped in cotton wool and be treated as though it can't handle any sort of conditions apart from being pampered in a very rigid set of "ideals". They have thrived and survived for Millenia, without any sort of princess treatment. Hope this helps,..... Organoman.

RH never bothered me with seedlings, but Henry's right about the temp, 30c is a bit high

That's a high RH. I would aim for 60-70%. And 30C is pretty hot. Some strains might responds pretty well to it, but as a rule of thumb, I try not to exceed 28C. I don't think this will cause any lasting damage, just get them in the proper conditions and don't overwater. You might lose a couple days of growth. No biggie.