My DS is 4.5 months old and in the last week or so (it's very recent) he gets upset when strangers look at him/hold him. He just bursts into tears. This actually included my MIL who he's seen a few times but doesn't know her well. He's all smiles with me, DH, DS1 and my own DM who sees him once or twice a week, but at a family event last weekend and then again today (different people) he burst into tears almost as soon as anyone new looked at him or held him.
Is this normal? It seems very early for stranger anxiety. He's a very smiley baby with just us, always laughing and looking around curiously. He smiled very early (3 weeks) and also laughed very early (9 weeks).
I'm anxious about this as DS1 (age 3.6) may or may not be on the spectrum.