Yes, I got them as well.
I just received 2 letters from TSP in the mail dated June 4th. One was about "Your account has been claimed" and the other is "You added and alternate email and changed your phone number" I don't know what "your account has been claimed" means. I assume these are just letters to confirm I've switched over to the new system successfully? I can log in ok and all my data looks normal. Just was curious if anyone else got these kinds of letters.