We never saw it with DD - just thought rearing DC in general was hard. Montessori raised it with us in at one of the regular developmental meetings (every 6 months), had we noticed anything, they had some concerns, here were some specifics, and it might be an idea to get her assessed. But that she was still a lovely girl and talked about both her positive and negative things - so a mostly regular developmental meeting in that respect.
It was an utter shock to us.
But when we sat back and thought about it, lots of things then made some sense.
We asked GP about it, and a referral was set in train. DD started school about 4 months later, teacher dismissed it for ages, but at the end of junior infants agreed maybe it was something to consider. Actual assessment started Sept of senior infants (2nd yr of school) by which time things were becoming much more obvious.
If we hadn't started acting when we did, we'd have waited an extra 2 years at least for Dx, and longer for any supports.
As it happens, we have had to source and pay for most of the supports ourselves, including private assessments.
But it has made a big difference.
Partly because, knowing her dx (on the ASD spectrum), we have learned how her mind works and how to do things so that we can work WITH her and not always end up pulling AGAINST her. Which has meant that lots of things have gone better than they would have if we had stuck to what we were doing before.
And DD is still in mainstream school, does various activities outside of school, both individual and team activities, and is a happy DC. But we know what accommodations to make so that we don't have massive meltdowns (in our case - different parts of the spectrum have different issues, DD is high functioning).
So we are very grateful to the Montessori for not just noticing it, but raising it with us in a sensitive way.