Mimicking 3 year old speech

My son has developed a stammer/stutter. It happened 6 months ago, went away in about a month, but now its back.

He also uses W for his R's. Pawk vs park.

I think it's normal development. He talks like crazy, has always been beyond others his age in speech.

Is it weird that family and friends mimick or essentially make fun of the way he talks?

It bothers me. I dont think they're intentionally making fun of him obviously..but it's a reminder that his speech isnt perfect.

Anyone else deal with this or have any advice. Is this normal for others to respond in this way?