A: CO2 forming underneath your culture and pushing it up is definitely normal and not necessarily a sign of an off balance brew. We always want to see a decent level of carbonation in the first fermentation.
However, sometimes too much carbonation can be accompanied by premature souring and low concentrations of gluconic acid. This means your yeasts are overpowering your bacteria. Typically, yeast tends to go into fermentation early and begin producing alcohol along with relatively small amounts of CO2. This is good. But in the warmer months the likelihood of yeast being in respiration increases (basically yeasts overproducing CO2, underproducing alcohol, and then the bacteria suffer).
So what can you do to decrease CO2 (and therefore airpockets under your scoby/reduce early souring):
1. Increase the available glucose (add slightly more sugar next time)
2. Decrease the strength of the tea (add slightly less tea)
3. Reduce the temperature (try to store your jar somewhere between 70-75 degrees F)
4. Reduce the yeast population by making sure to pull your 1 to 2 cups of starter tea off from the top of your brew where it is bacteria rich. Yeast tends to reside at the bottom of the brew jar.