Separating route from mapped road

I accidentally did something that had the useful effect of separating the route from its actual road on the map so i could see the road itself, with the CT route separated from it by a little.  This seemed very useful for just seeing for example whether you're on a path or a bridleway in the UK - a designation that gets hidden when the route trace sits on top.  Trouble is, I don't know how I did it!  It seemed to go away when i zoomed back out.  

Did I just have a nervous breakdown, or is this a real thing?  And if so, how?  Many thanks to whoever tells me more...I have searched but i don't know what to call this behavior - slide?  Offset?