Great job feeding your baby!
So do you feel you're back on track today? It may be that you've had a 'bad' day and things are better now. Stress doesn't really affect supply, as such, but it can interfere with getting a letdown, which can mean you get less out - and over time, can thus affect supply as well. If it's an ongoing problem, perhaps you can try extra sessions at times when the expressing works better for you, so there's less pressure to get lots out at work?
Lots of breastfeeds when you're together will help, too.