I'm pretty sure this restroom is set up for testing. It's not the public restroom. The hallway goes into a room, and there's a sink and a door. Then you go through the door into another room, where there are two stalls. There wasn't a dying agent in the toilet, but she did put tape over the flusher.
Okay. What youve experienced was known as a monitored collection (as opposed to a directly observed collection) A monitored collection is utilized in two types of situations:

a) multi-stall situation - a monitor is assigned to prevent others from entering the restroom

b) Bathroom is such to where the sinks and toilet cannot be individually turned off (usually in ancient buildings to where the only shutoff is the water main outside, which turns off the entire building). A monitor is there to deter the donor from using the unsecured sinks and toilet to tamper a urine sample. The fact that the toilet bowl did not have any bluing agent was sufficient cause to assign a monitor to deter donors from scooping up the bowl water in an effort to tamper the urine sample.

In either case, the monitor is to remain outside of the stall (multi-stall), and is not there to directly watch the flow of urine exit your body and into the sample cup (thats the job of the observer in D/O situations).

However, if a monitor happens to suspect any tampering going on in the stall, the monitor can stop the collection and bring it to the attention of the collector, who would immediately order a D/O collection.