The German attacking midfielder was a surprise guest of his former club Ingolstadt on Friday as they played a friendly against local side Wurzburg Kickers during the international break.
Gross, who achieved promotion to the Bundesliga with Ingolstadt in 2015 before leaving to join Brighton last summer, enjoyed his afternoon at the game.
"I always like to come here, after all I have played here for five years and have many good memories," he told Donau Kurier.
"I watch almost every game for the full 90 minutes - Ingolstadt has recently improved, plays convincingly, which is certainly a great credit to the new coach. Trust them and they can be promoted."
The 26-year-old had words of caution for those thinking Brighton, who sit eighth in the Premier League, are secure in mid-table.
"It's going well for us at the moment, but we should be careful," he added.
"The season is still very long and it would be great if we could retain our Premier League status."