< 1000 miles on a 2011 bike with 105 components. The right STI shifter is not feeling very crisp. Kind of "mushy" if you know what I mean. A few weeks ago (when it was colder), it wouldn't even return all the way when up-shifting. That is, I would do a full press shifting three gears. And then if I did a single press to shift one more gear, it wasn't catching. Well haven't noticed that with a few more rides and warmer weather.
Several months ago I did a 62-mile ride in the rain. Maybe that is related.
1) squirt some light lubricant in there (i.e., no WD-40)
2) replace cables with higher-quality stuff.
These days I prefer to do my own bike maintenance, but I will take it to the shop if they've got magical means of making these things work better.