We had a similar thing with our granddaughter at school. We went for a walk with our son, and two of his children before Christmas, as we were allowed at the time. The following week, a child in her class tested positive. Originally...it wasn’t a friend, but then someone in her friendship group tested positive. They were all sent home when the first child tested, but after it was one of my granddaughter’s friends, her parents had her tested twice. Negative both times, but she had symptoms in between, loss of senses, feeling sick.
Try not to worry Whiff. Maybe a test for your grandson would be prudent, but sadly....yes, in answer to your question, you could catch it.
I’ll pray you haven’t ?