Other planefags….. have a question.

I’m in the mountains of East Ky, and just a few minutes ago (12:20pm est) at least two fighter jets were buzzing LOW. I’ve lived here for 5 years, and this was the first time I’ve ever heard them, so they aren’t a regular occurrence. At first I was like, cool, they are training and figured it was T38’s. Pulled up all my tracking stuff I normally watch, etc to see what they were. Nothing is showing up, I heard a second one coming and ran outside and put a visual on one and was able to snap a picture before it was out of site. It was not a T38. I’m sure they are training, but it is normal for training to have transponders turned off?