I agree with GLC1968. I started gaining weight recently after initally losing it when I began riding, and I didn't THINK I was eating differently. Fortunately, I'd been keeping track of my food intake on fitday.com while trying to cut fat, and as I look back I realize I'm actually eating about 4-500 more calories a day than I was a year ago. So it might be worth looking into....
OR, it might be muscle gain....
If your clothes still fit the same.
Now that I look back I see that you have been keeping track of your diet, so maybe it's the muscle thing....