Nope, it's all in your head.
You will find a lot of people agreeing with you. One thing they have in common is that they don't have the data to prove it.
the qualitiy of my drops
[...]
a semi usable OS shield
Both subjective and vague, thinking in those terms allows the psychological effect to happen, seeing patterns in randomness. The only prerequisite is a low probability for your preferred event. For the average hard mode chest, the probability of any gold dual mod shield (regardless of which mods) is around 0.6%, meaning you get one in every 158 chests on average. Then you further reduce your chances by only preferring certain mods (I wrote a little about that subject here). You can imagine, with your own weekly chest running rate, the difference between completely normal rng variation results in a "lucky" week with 10 good drops, or an "unlucky" stretch of 5 weeks or more. From my own chest running data, I can confirm Red's statement that there is no correlation between good drops and time spent on the run. I can also confirm that it really does feel as if my drops are better when starting a new type of run or farm 
If anyone has further insights, I kindly ask them to also explain to me why I always end up in the slow line at the supermarket checkout, why it only rains during my weekends when I planned to be outside, and why the restaurant has always just run out of the menu item I really wanted...