The 300 is a whole other animal than the 300ER, almost all the weight but a lot less blow from the Rolls Royce engines. Combine that with 50+ degree temps (I don't care what the metar says, I've lived here too damn long and know how hot it was yesterday) and probable low level wind shear and more than likely a late go around decision found them in a low energy state. When exactly the gear came up we'll soon know, but those gear doors aren't exactly small either.