Nessa, I have the same problem - and its always silly little things too!!

What I do is write down what annoying me on a sheet of paper and fold it up and put it on the fridge for later - then dont think about it til later. A couple of hours later, I ll read all the notes on the fridge, and if it seems silly or not important, then it goes in the bin and I know I dont need to stress about it.
If the problem does really need to be addressed, then it goes back on the fridge until the next day, and then it gets addressed with cool heads.

The best thing is "Will this matter in 2 years time?" If it really wont, forget it, and move on, if it will, address it later on when you can think objectively.

A little OT, but when you are having troubles with something the DH is doing/saying/being etc, when talking to him about it, say "When you......., I feel........." rather than just getting mad and confronting him. My DH doesnt do confrontation, so I had to learn how to be upset and angry and still get through to him, and this technique helps us A LOT!
Good luck!