You noticed. Spencer had a bad tendency to hide things until it became so painfully obvious for everyone else; he had his reasons, sure, he didn't want to be treated like a child. He didn't want to be treated like he was crazy.
Reid knows his hands are shaking as they were presenting the profile for a schizophrenic unsub, he knows his neck twitches and that no matter how much he knows everything to know under the sun, he still doesn’t know what's wrong with him.
And storming off in the middle of a briefing doesn’t help his case. When you walk in the men’s bathroom, he is washing his face, looking like hell, even if he hasn’t told anyone, he tells you.
“All the doctors say I'm fine but — I have terrible headaches, I can't sleep, I can't concentrate and I've only read five books this week.” Spencer lists off then, as if showing everything he's been trying to hide, all of it blowing up in his face, his back to the mirrors.