I signed up half an hour ago, and I skipped the tips for new users, being already accustomed to it, and once I became a basic user, I got 6 times the welcome message for becoming a TL1.
As soon as I dismiss the notification in the notification shade, I receive a new one a minute later. If I don’t dismiss it or click on it, it stays here and I don’t receive any new one.
Edit: Seems to have stopped now. I didn’t receive any new one for 10 minutes. Happened again a few minutes after my edit.
Edit2: Happened twice again, though it seems pretty random.