Stranger Anxiety Phase - Anyone else?

My son started a few weeks ago. He cried and hid against me when his grandpa visited and instantly walked up and patted his head. I had to remind him to let Roran adjust to him first. Roran loves other babies and little kids instantly, but is very shy around adults other than his parents.

Other times he's suddenly a social butterfly, doing his 'hold me' dive towards a stranger in the checkout line like he thinks I'll just hand him over to them. A rarity, but funny every time.