I just took 16 cuttings Sunday, only 2 "drooped" on Monday. Foliar fed them, and they bounced back up within an hour. Non Ph'd well water, dipped cuttings in Aloe slurry, 2 Tbsp Azos added to water, plugged cloner in, and away we went.
Temps in room are 75deg, 55%RH, no dome, and none of them have dropped since Monday, have always run my cloner the same exact way, and have had 98% success with them rooting.
I wouldn't say your cuttings are too small, give them some time, in the past, some of mine have drooped, but they always seem to take. I made a homemade cloner about 12 years ago that my buddy still uses to this day with just a small tub, an air pump, and 2 air stones, and he has around a 97% success ratio. I wouldn't worry unless they start to dry up, keep them under LOW light, I use an old T8 fixture with plant bulbs, 56 watts, foliar feed twice daily and they always seem to sprout roots in 7-10 days.