Golf 1.4 Smoky exhaust. HELP!?

Hello all, i recently bought a 1.4 petrol golf year 2000, when i bought it there was no smoke coming from the exhaust, however today while it was raining i noticed a small bit of white smoke coming from the exhaust,,, any ideas? Is this a big deal? Could it be somthing to do with the rain? Can somebody help me please!