What makes you think I’m trying to groom you?

Make direct eye contact and say “Why are you paying such close attention to me? It feels weird.” It’s unexpected to have a young kid be so forward and direct, you’ll likely catch them with their guard down. If they start to stutter and are clearly caught off guard, you can be sure that your intuition was correct. Don’t ever, ever feel bad for making an adult uncomfortable or calling them out…they are the adult, they have the responsibility in that situation.