I need help with TriCare?

I just recieved a letter in the mail from TriCare stating that I have a $3,840 claim that I owe. I didn't even know I was on TriCare. What is going on? I used to live with my uncle in Texas (when I was 12 I am now 21) who was retired from the military and i'm assuming this is the insurance he had me on back then but why am I getting letters from them? I don't even have a military I.D. anymore and I have never told any of my healthcare providers to charge anything to TriCare. Was my uncle supposed to let them know that I moved back to my mom's when I was 14 and that I was no longer living with him? Someone please help me as I have no idea what is going on. It says that *I* had medical services and an x-ray done on 6-24-10. I was pregnant at the time and did NOT have any type of x-ray done. My husband was injured at work and had an x-ray done on that date but it was all covered by Pinnacol through worker's comp. Why is TriCare claiming I had medical services done when infact it was my husband and NOT me? What is going on? Please someone help me understand as I am very confused and don't want to get into any trouble. Thanks..