Anyone else experience this?

Last night I had my 8 week old on the changing table and I watched as his face got real red and his arms and legs went out to his side. It only lasted a few seconds but then it was like he scared himself and burst into tears. It's nothing I've seen him do before. I was concerned it was a seizure and called the on call doctor who assured me it wasn't. He did it a couple times this morning and it still freaks me out. He used to love his nursery, no matter how mad he was he'd smile in there. Anyone else experience this or am I overreacting?