Jessica Simpson was seen with her supposed former flame... comedian Dane Cook!

Simpson watched him perform at the Laugh Factory Tuesday.

Dane was happy to have old flame Jess there and even sent over a round of drinks to her table. He then invited her backstage after the show, natch.

A source says, "Jessica seemed so excited. Once the show ended, Simpson was taken upstairs to the VIP area where she and Dane flirted and had another round of beers.

"The staff left, but Jessica, Dane and her four friends stayed in the VIP section after hours."