I hate being negative like this, but I hate how my brain just won't let this interaction go. My brain still thinks it needs to prepare itself for something when the event has already happened and the person who caused the interaction in the first place, has likely already forgot.
It just takes one person to ruin your entire day. Just one person who talks to you for 30 seconds. Screws up everything, your work ethic, your apetite, your sleep schedule, everything. Ruined.