heartshapedglasses

Just got it a few weeks ago and the other day I was going flat out at 50 mph on a dual carraigeway when it started to slightly shudder and then slowly lost power until I had to pull over and call the AA. It was pouring down with rain so could that be a factor? It's 4 yrs old but has been kept in storage until we got it, with 800 k's on the clock. I've pushed the distance up to about 1200 k's now with going back and forth to work so it's only just run in. Is this problem something I should expect under the circumstances, or is there a possibility of a problem somewhere? I have ridden it since it broke down and it seems ok but I'm worried about going on the dual carraigeway again incase the same thing happens.