This sounds really creepy to me, and it just might be over the suspicious line to more than that. Keep your eyes and ears open. And maybe it's a good time to just have a general talk with your boys about "stuff". You know, the no touch rule, no secrets in our family rule, blah blah.
I have a good friend who set up a code word with her kids. If, for any reason, the kids were in a bad or uncomfortable situation, they could call her (or their dad) and say into the phone, "Aunt Charlotte texted me to call you." You can use any name you want, but something you mutually agree to. The day one of her daughters called and said that to her (in the middle of the night), she jumped in her car, no questions asked. Turned out everyone was drinking and were about to get into a car and the driver was her ride home. You can use it for just about any situation out there.
I always thought that was clever.
Do you have any cop friends you could go to? I think I'd start there anyway. This sounds really sketchy...
Good luck-Betsey
"There are only 2 ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle."