The 23-year-old was sprung commenting on a ten day old Instagram snap of Simmons, sharing a cryptic teddy bear emoji.
Instagram account @commentsbycelebs quickly captured the comment and shared it on their own profile with the caption: "10 day old picture, 6 minute old comment. Kendall, she creeps just like us."
The supermodel has been spotted at a number of the Philadelphia 76ers player's basketball games over the last month.
"Kendall and Ben have been making more of an effort in their relationship recently, and have been seeing each other regularly for the last month now," a source told E! News. "They both are very busy with their careers, but have always been in touch."
"They never had a falling out, it was just always hard for Kendall because of her work schedule," the source added. "They reconnected when Ben was in town recently and have been seeing each other since."