Nicki Minaj's Ex: I'm Over Dat Ass ... And Onto K. Michelle's Booty

According to our K. Michelle sources, she and Samuels have been getting much closer lately ... talking and texting every night.

We're told the duo spent two hours together in the VIP area of NYC club Stage 48 on Valentine's Day and Samuels followed up this week by sending a bouquet of sunflowers ... her favorite.

Our sources say they're not official, meaning exclusive ... just yet -- but this video K. Michelle posted of herself twerking to Safaree's new song has to count for something!