One of my Breasts is Harder Than the Other - Why?

I am 32 yrs old and I had breast implants (Natrelle Saline filled, 450 cc in each) placed about 2 yrs ago and haven't had any problems, but about 3 days ago I noticed my right breast is harder than the left all of a sudden. It doesn't look any different, just feels harder than it had before. I am just concerned that something is going wrong with it. I am right handed, would that have anything to do with it, since i use the muscles in that side more? Should I see a Dr?