"I saw them at Nate 'n Al in Beverly Hills and it was clearly a date," an eyewitness tells us.
"He paid the check and as they left, he had his arm wrapped tightly around her waist."
The pair split apart as they exited the popular deli, with Martin holding the door for Heidi and the kids and then walking several steps behind the supermodel.
Klum's estranged husband, singer Seal, went on the offensive in their divorce war on Friday, accusing the Project Runway star of cheating with the bodyguard while they were still together.
His fury came on the heels of Klum and Kristen being spotted getting cozy during a recent family getaway to Sardinia.
As RadarOnline.com has been reporting, Heidi and Seal's divorce battle has been heating up over the last several months as they battle over child custody and finances.