Strange disk shaped object hovering at the side of a building in Manila, Philippines.

I am a female living in the Philippines.  I was a 4th year nursing student when I saw it, but I can't remember the exact month and day only the year.  Where on a bus on the way to our community service in Cavite.  It was around 9:00 am.
When our bus neared Magallanes Flyover, I saw something hovering at the side of a building.  At first I thought it was a balloon, it was silver in color and disk shape.  When the bus continued to the flyover my view of the thing was blocked, but when I have a good view from the bus again the thing is now gone.
After 3 days our community service ended and I returned home.   I told of what happened to my husband and he said it might be a ufo. I never believed in ufo’s before but now I do.
Source of report indicates that the date of the incident is approximate.  PD