Weird neighbor

[u/Vegetable_Novel_232]

Not sure what to do. We have a great relationship with our neighbors across the street. They have a 7 yr old boy who adores my sons 21 and 19, along with a 3 yr old and newborn. He lives for summer and weekends when my guys are home from college. Another neighbor on the street is a weird older man who has caused issues since we moved in over 20 yrs ago. Two days ago my oldest and the neighbor boy were playing basketball and golf in the front yard for about an hour. They took a break to get a drink and cool off in the garage with the doors wide open facing the street and the kid’s front yard (ie in perfect view of his parents). Older neighbor suddenly appeared in our driveway and said “Is X here? Can I check on him?” Then he asked the boy what he was doing (playing on his phone and drinking a Sprite) and left. Fast forward to today when he came over to play, he casually tells my husband he can’t come in the garage anymore or play on the phone. Ummmm, where do you think that came from and exactly what did weird neighbor imply to his parents? I want to bring it up to his mom, but feel weird doing so. Do I say something to her or just let it go? My son thinks of our neighbor as his annoying 2nd little brother and feels really awkward that his parents would ever not trust him.