Mystery solved

Kyle: "Mom, I'm not a baby anymore. I'm almost 9 months old y'know."

Mom: "Yes son, I know."

Kyle: "I'd like to sit up to the table to eat now, in my booster seat. I'm too old to use the high chair tray anymore."

And so, Kyle now uses his high chair in booster seat mode and sits up to the table with the rest of us to eat. He polished off almost a whole jar of chicken and apples tonight; back to his usual solid food appetite. Whew!