Speedometer

I was driving home last night and my speedo needle jumped up to 60 and then down to zero for about 3 minutes. As I was continuing to drive it started jumping again and then returned to normal. All the other instrumens were working fine. Could the speed sender unit be on the way out? Has this happenned to ayone else? It's just that I'm driving through Europe next week and I'm a bit worried it's going to die on me. In France they just fine you on the spot and demand cash up front.

Cheers, Nick.