Geckos regurgitating Food

[VintagePArk]

hi there I hope the brain trust can offer advice, I have a rack of geckos and a couple started regurgitating food, two older 4 year old Wheeleri, I checked temps they seem to be around 30-31 on the hot spot and around 27 on the cool end.. I fiddled with the thermostat and reduced feeding the entire rack for a week and went to feeding twice weekly as many as they eat at a time, and seemed to stop but this week 4/7 racks had regurgitated feed an old ages and breeds of nephrurus. They seem normal in all other aspect and have passed normal waste. Any advice greatly appreciated