What is your soil mixture like? If you're using a medium that already has slow-release nutes premixed, then you probably shouldn't be feeding any supplemental fertilizer to the plants. These soils generally have enough fertilizers mixed in to get the plant through a month or two of vegetative growth, and adding more could contribute to overfertilization.

At first glance, I would also have thought that overwatering was the problem. But with that much perlite in the soil, I'd say that this would be pretty difficult to do.

You could add a drop or two of dishwashing detergent to a gallon of water, and water the plants with that next time. This'll act as a wetting agent, and will help the soil absorb water more evenly for the next few waterings. Keep us updated.