Abnormal liver function tests can mean many things or nothing. Sorry if that sounds vague.
Liver function tests are a bit of a misnomer as the test is actually a group of tests that looks for different things. For eg. Bilirubin can be elevated if you have Gilberts Syndrome. This is a benign condition that causes a raised "LFT" but only one part of the LFT panel is elevated.
Apart from the well known causes like Hepatitis there are many other things that can cause abnormal LFT's recent viral illness/infection and some medications including panadol that can cause raised LFT's. Other things which can raise one of the panel of tests include a recent bone break (this can raise the Alk Phos), or bile duct obstructions high fat diets, etc.
I wouldn't worry yet until you need to. Or if you need any further advice (I was a Biochemist in a medical lab before I started my career as a Mummy) ask your Dr which of the LFT's was raised and I can try and put your mind at ease. You can PM if you like.
Your Dr is being thorough by checking things with an US, try not to worry.