is it normal for 2 year olds to start saying something wrong that they used to say (almost) right

[nappyaddict]

Ds has done this with a few words recently. an example is Grandma. He has always said it as Gah-ma, but now he has started saying Mah-ma.

I think it's just part of the map of speech and nothing to worry about. My Ds used to call my mum Mam ma too...we all loved it until he changed it to Grandma.
Don't you find it endearing?

My DD 2.6 has started this too, she mastered Grandad, but now has starting calling hime Dad, simply because she can't be bothered to say the whole word i think.

My dad just doesn't answer until she says it right again. Shes also got in the habit of going back to baby talk eg. a dog went from a woof woof, to a doggy and then to a dog and now its back at woof woof again.

So normal IME