I've had this happen, here's how I handle it.
First, set down the #3. In my book while the #3 can usually be a 10 second pick, due to the looseness of the plug and overall crapability of a lot of Master locks, sometimes they just don't cooperate. The high angled keyway also gives me issues sometimes. Most Master locks even prevent me from using my favorite picks.
I'll shake my hands around like I'm having a seizure, crack all of my knuckles, do something else for a bit like play a game or whatever then take another crack at it.
Also, check up on your tool maintenance. Perhaps your picks are getting rough, which can throw off your game. Nothing feels more smooth and crisp than a pick with a mirror like shine to it. Check out this recent write up if that statement loses you
http://www.lockpicking101.com/viewtopic.php?f=4&t=60309.
If I can't pick to save my life on a random day, I'll go over those things I've mentioned, and take down my speed to much much slower.