The Twilight stars, who have been the subjects of constant romance rumours, were spotted late last week at Bobby Long's show at Hotel Cafe.
An unidentified source told People: "Robert was super low-key when he walked in.
"Kristen and Rob, just the two of them, came in and walked towards the curtained-off area on stage where they watched Marcus. They seemed to go unnoticed."
Long reportedly joined the pair following his set, as the trio jumped into a waiting cab.