I need advice following a casual comment from my toddler's nursery...

Hi, I'm new. New to this forum and new to thinking about autism beyond what I've seen on tv or heard on the radio.

I have a 2.5yr old son. Talking to his key stage worker (KSW) at his nursery yesterday I asked what they mean when they say "you know what he's like". What is he like? I asked. We only have one child so I have no frame of reference.

His KSW casually said that my son can have emotional reactions to situations which are disproportionate considering his good language/communication skills, and that can be a sign that he is on the autism spectrum.

He said it was 'something to look out for' or 'keep an eye on', I forget which. 

So now I'm trying not to project this throwaway comment onto him and I'm frankly a bit confused about what to look out for and how to look out for it and what to do if I notice it. 

My son is generally a happy, affectionate, articulate little boy. Should I just forget the conversation or will I potentially help him in the long run by assuming he may be on the spectrum?

Any advice greatly appreciated.

Tim.