DIY incubator temp questions?

Okay so I have a broody hen sitting on some eggs rite now but she is only about ten months old and this is her first time going broody so I was worried that she might get off her eggs half way through. So just in case I decided to make a incubator out of an old cooler and a bunch of stuff I found in my basement. The only thing I bought was a small thermo/hygrometer from Canadian Tire for $9.99. I put all the pieces together and I have three thermometers inside just to be sure. The digital one has been reading 99.5 to 101.5 for a day now, the regular type one that you would have outside your kitchen window reads a bit lower around 97 to 100. I also put filled a small balloon with water and slid a aquarium thermometer in to the balloon so it is suspended in the water and it reads an all most constant 96 degrees.Does this sound okay? I had three so if one was different I could still be spot on with the other two but I did not expect to have Three different temps.