iPhone 13 Pro Making Multiple Calls on its Own; Line Left Open

Yesterday while I was on a walk, with my iPhone 13 Pro in my pocket, the phone made 3 different calls all on its own, for a total of over 50 minutes. The last one was still ongoing when I took the phone out of my pocket and discovered it. All the calls were to numbers that were on my Recent Calls list. Has my phone been hacked or is there a bug in the software? I never pressed a button. I walk with my phone in my pocket all the time, nothing like this has ever happened before, and then suddenly it makes 3 different calls all on its own.