Hi hibeeslass, It's not uncommon to see some moss on lawns at this time of year when the ground is wet and sticky. It's often regarded as an indicator of poor drainage.
It can spread if you leave it but if it's just a few patches it can easily be eradicated by scarifying, a wire spring rake is best, the type thats handy for raking up leaves.
If you repetedly rake over the patches, you will eventually scratch out the moss, once this has been done you can start on the cause of the problem and push the tines of a fork, as far as you can into the lawn this will allow the water to drain away much quicker and also airate it too.
To improve the drainage further, you may want to get some horticultral sand or lawn sand and brush it into the lawn unto it all disappears into the fork holes.
Hope the moss is'nt too extensive otherwise it would be worth while doing the whole lawn like this.
Good Luck Tbird+
Ps sprinkle a little grass seed on the pathes afterwards, mixed with some compost or fine top soil, covering with a piece of wire mesh will help keep it from being disturbed while the seed is germinating.