Lately it started happening to me much more frequently that my hands "forget" what to play (while performing), and I try to hide my embarassment by improvising something and then getting back to the tune. Maybe age? I'm just 44... As to tilting the pick - I mostly use alternate picking, doing tremolo-like movement when playing fast. When moving from one string to another, I tilt the pick slightly down when I need to strike the "new" string from below (i.e., an upward stroke) and slightly tilt up when striking a string from above.
Having a great mandolin makes it more tempting to stay with it. I know my right hand technique for guitar is pretty different from my mandolin technique. It might be string spacing or playing double strings versus single...whatever it is, one style doesn't fit both.
I'm also taking a closer look at my right hand technique, specifically how I attack the strings .Coming from guitar I didn't really adjust anything when I started playing mandolin, I already held the pick like most mandolin pickers do, so I kind of just winged it. There's a lady at my jam who can just pull so much cutting volume out of any mandolin she plays. I think I'll talk to her and try and get some pointers Keep on persisting! It's easy to persist with that excellent Red diamond you have though isn't it!
Mostly, I think my problem is advancing age and a family tendency for arthritits. If I can avoid the high-speed tunes, I'll continue to play as long as I can play in time, and produce a good tone. After that -- well, we'll see. =^)
I can identify some with you here: I think it may have something to do with adrenaline...maybe.