Shimano Deore front derailleur occasionally sticking
Put some chain lube (Triflow ftw) on the pivot points of the derailleur and go through its full range of motion a few times. You should start feeling a big difference. Also, you may find replacing your cables and housing to be beneficial - very easy to do on your own and relatively cheap to be done at any local bike shop.

Tip: WD-40 is not good for bike components. Use it to free up rusted screws- that's it.