Twitter people are actually calling for a petition to reunite Johnny and Kate, and although it's just chatter ... it does seem Kate is still very fond of her ex.

As we reported, Amber had testified about an incident where she claimed Johnny was about to attack her sister Whitney on a staircase when she stepped in and swung at him. She said she feared he'd push Whitney down the stairs because she heard a "rumor" Johnny had pushed Kate Moss down a flight of stairs in the 90s when they were dating.

Well, Kate blew up that rumor ... blew it up to smithereens, when she testified via video that she did indeed take a plunge down a flight of stairs, but the culprit was rain. She said she screamed in pain, and Johnny ran to her, scooped her up, took her inside the hotel room where they were staying and got her medical attention. In other words, it was a gallant act on Johnny's part.

Twitter folks called Kate's testimony "true love," while others observed Johnny seemed to light up during her testimony.

And, get this ... one person wrote, "I hope after this is over, Johnny realizes Kate was the one to marry as a life partner. I hope he phones her up and asks her out on a dinner date."