I can think of a reasonable reason that CT's phone contacted MB's phone. If CT had tried to contact AJ and she couldn't reach him for whatever reason, (his phone was turned off, going straight to voicemail. he didn't have it with him at the moment, battery died), she could have called MB to ask her if she's seen AJ or to have AJ call her. I can see her thinking to call MB versus someone else because AJ had been training for CG and she knew MB would be there.
A slightly different scenario happened to me recently. I knew my brothers were at an event not together but didn't go together. I was trying to reach one but his phone kept going to voicemail. I called the other brother to ask him to have the other brother call me if he saw him. As it turned out they were standing next to each other so I was able to talk to him.
Of course the other side of that is that CT couldn't reach AJ and called MB's phone to see if she was unavailable also. But that doesn't mean she's swatperp because she's suspicious.
A possibility. More likely an intentional call from CT to MB.