So you just left that restaurant with those employees thinking they were possible victims of a terror attack?
What about the business that they possibly lost because they had to clear the place out?
Admittedly the scenario is humorous on the surface.
BUT, you are still the individual directly responsible for disrupting a business and possibly costing them money in lost customers.
As well as lost time in investigating the source of the contaminated air.
Since they serve food to the public I'm certain they were doubly concerned about an unknown airborne contamination source.
So while I'm not going to fault you for the location of your OC Spray I AM going to fault you for the irresponsible and very immature way that you handled the scenario as soon as you realized that you were responsible for the evacuation of the business establishment.
What IF you cost them a few hundred dollars in lost business revenue?
The entire situation was unintentional (on your part) but you still need to "Man Up" and make a phone call & explain what happened and offer to make good for any losses that you caused.
Just my personal opinion on that.