I was just wondering if Helen/Elastigirl has some kind of super-sight power? Because she noticed a very little piece of rubble in Bob’s shoulder from feet away, a single hair in his clothes and the patch on his suit (while it was quite dark).
May be it’s just me, but it’s weird how she noted all those little things.
You know how easy it is to find things that you’re looking for? Helen was suspicious as to why Bob was so late, so she was probably looking for something that had to do with his super strength.
I think this could be a better explaination. Bob’s jacket was pure dark black. On his shoulder was grey. I bet Helen can assume that the gray stuff didn’t get on Bob’s jacket by itself. He probably did some super hero work.
Maybe superheroes have been trained somehow to have really good eyesight and catch little things. After all, it’s important for them to notice things that can be clues. And even though they retired at that time, she couldn’t give up the skill she gained and used it. (just my thoughts)
Oh, I never thought of it that way. That seems like good explaination.
There’s also the fact that Helen is now a housewife, after all. Housewives have an uncanny way of noticing things that are different within their own homes, because they see the same things day in, day out.
i wondered about how she noticed that piece of rubble too. I know i wouldnt have. But you know, wives and mothers always seem to know when you been up to something. it’s like an extra sense they have. The fact that Bob came back so late was what immediately let her know that something was off.
She’s a mom, she notices things. She’s like my mom- she doesn’t miss a beat. 
And most supers probably do have enhanced senses; but they don’t necessarily have to be super powers.