My mother was a speech pathologist and a childhood language specialist, her mother was a kindergarten teacher and a reading specialist, and her stepmother was a speech therapist and special ed teacher ...
From what I've gathered from them, I'd say lay off.
And all of them HATED what No Child Left Behind and other recent trends in pushing reading skills did to childhood education. One calls it "No Child Loving Books", and noticed how the NCLB curriculum led to kids who could read earlier, but couldn't strategize about cutting one object out of a page from a book of stuff.
Here's how my mom put it ... she'd explain that language (understanding words, being able to communicate with words and body language) is a brain thing, while speech (pronouncing stuff) is a fine motor skill. Reading (understanding how written symbols represent both language and speech sounds) is yet another skill. And to never sweat a small hangup on one detail of any one of those.
My kid, for instance, has spectacularly unclear speech. He's over 2 1/2 and we can't understand much of what he says. But he understands everything we say and he communicates what he needs very well ... he just has a fine motor skill issue that probably has to do with his not eating a variety of foods that exercise the 100+ muscles involved with speech. Like walking late or having trouble with scissors.
So you're right. It's better to let this one tiny detail rest a bit.
If you are concerned you can look up age milestones on www.asha.org
. There are also courses such as this one
for parents to understand what to worry about and what not to, and how to follow your instinct and use what comes naturally to teach your kid. (disclosure: My mother originally wrote that course many years ago, but she since passed and it has been modified and is taught by somebody else, we don't receive any royalties anymore, so there is no current affiliation).
I'm also reading a really interesting new book, How Children Succeed, that also gets into what we should worry about and what we shouldn't.
Way to go for homeschooling your kid!