If they are copepods, then no worries. Do they look like tiny little bugs? IF so, then that is likely what they are and your fish will appreciate the snack when they come home.
They don't really look like pods to me, but the pic isn't close enough to tell. I would swipe the glass with your mag-float and see what happens. If they brush off easily then wait to see if they come back and how quickly. You first said they may be bubbles and if they come back quickly then that would be my guess.
Is there any chance of a closer pic? Can you try to scoop some out of the tank and take a pic with a magnifying glass or something?
They don't really worry me since it is likely totally harmless, but now I am curious.