What you describe can happen to any brand. I used to shoot Canon, and some of my most precious and expensive lenses were filled with dust particles. Not a pretty sight, but fortunately not visible on any photo... You might want to take a look at the famous
Lens Rentals blog articles that support what I noticed for myself. None of the many lenses I possessed over the years (Canon, Sigma, OIympus, Panasonic, Samyang) ever developed any defect...
Cameras are delicate. My first two SLRs (a Praktica and a Minolta) suffered from a broken shutter curtains. Both of my Canons (a 20D and a 40D) had to be repaired, because the mirror mechanisms became defunct. My Olympus E-M5 Mark I developed hairline cracks in all corners of the enclosure of the rear screen, which did not affect the functionality. I had an E-M1 for a short time (we did not bond), and it had a failing rear control wheel and 'golden' specs on the EVF, which was a well known defect at that time.
My current cameras are a Panasonic GM1, an Olympus E-M5 Mark II and a Panasonic G9. None of these have suffered from any defect so far...
Friends of mine that have used Fuji and Nikon have had their share of defects as well...
I would say: as long as image quality is not affected, just shoot on. Else, send the device in for repair. Better that than to just give up and replace them.