I agree, it sounds like excitement to me.
Make sure that you don't scold her when it happens because it can then turn into fear and make the situation worse. And as with all house-training make a big song and dance when she pees in the right place, lots of praise and treats or play.
When you or new people greet her make sure to do it calmly. Loud excited 'puppy puppy puppy!' is not helpful. Think of a behavior that you would like her to do when meeting new people and work on rewarding that. For example you could train come, sit and shake hands. If even this is too much excitement try the following.
"The best treatment for excitement urination is to prevent your puppy from becoming overly excited in the first place. You can do this by exposing your puppy to the stimulus that excites him, over and over until it no longer excites him. Most likely, your puppy gets excited and wets when you return home. If so, simply ignore him for several minutes. Don't even look at him.
Then leave again for a few minutes, return and ignore, leave, return and ignore. Keep doing this until you can see that your puppy is not only unexcited, but is actually getting bored with the whole thing. If excitement urination is a problem when visitors arrive, have them do this too. When your puppy has calmed down and is no longer excited when you come in, then very quietly and gently say hello. If any signs of excitement or urinating appear, quickly exit and repeat the coming-and-going routine. A rapid sequence of heel-sits will capture your puppy's attention and channel his excitement to the game of heeling and sitting instead of urinating. Remember to ignore all excitement urination and never scold or get angry at your puppy when it occurs."