That is true for the 'muon flux' app, you want this one instead:
http://wipac.wisc.edu/deco
Very interesting. I'm really skeptical, since CCDs are highly sensitive to infrared, and thus have a high amount of charge background (working with CCD cameras for dark field imaging teaches you a lot of their physical aspects and limitations). Phone CCDs are even worst, with very small wells (1.2-1.5 um^2 and such for high MP cameras) that have very high current noise in pure dark just from natural electronic current jitter, and low sensitivity (due to the small amount of liberatable electrons in such a small area). Particles like muons would be both rare and not cause a lot of charge displacement, so I am doubtful they'd be above the electronic or IR noise for the low sensitivity of cell phone cameras.
But, love to see hard data showing if it does work!