What are UK immigration officers looking for when confirming Registered Traveller status?

I recently applied for, and received provisional acceptance for, the Registered Traveller service. I am a US citizen and frequent traveller to the UK (2-3 times a year), with absolutely no record of issues whatsoever.

I will be in the next couple of days going to the UK. The UK government website says that, when I arrive in the UK:

The immigration officer will check that you meet the criteria and tell you that you can become a member if you do.

I am a little confused by this, as I already provided all of my details to demonstrate that I met the criteria for this service. What exactly will the immigration officer be looking for? Simply that I exist? Do I need to bring any paperwork, or expect any additional questions (i.e. additional to the "standard" questions asked of all visitors)?