Should I be weary of naming my business something that may already be registered in the US?

We're based in Canada and are in the process of naming our new business for registration in Canada. We're going to be developing mobile apps.

However, we've run into some issues. The name we decided on is not registered in Canada, but we think someone in the US may have recently registered it in the US. However, we haven't been able to find a way to figure out for sure. We're now wondering whether or not it's a good idea for us to use this name, since we'll evidently be selling to people in the US.

If it turns out that someone in the US has already registered this name for their company, is it likely that we could end up with a law suit over our US sales? Has anyone experienced issues similar to this?

We're trying to decide whether it's an issue worth consulting a lawyer over or not, so any input would be appreciated.

Simple answer, yes consult a lawyer.

More complex answer, in the US (and elsewhere) trademarks are meant to prevent consumer confusion. Whether you will face, or prevail in, a lawsuit depends on how close the names are to each other and the markets that the names are being used in. For example, your might create software and the other person with the similar mark might be in real estate. In this case you might not run in to any legal trouble. On the other hand, if you are in the same or similar markets, then the other company would have priority and be able to prevent you from using the mark.

A lawyer would be able to evaluate your mark, do a search for similar marks, and let you know any risks that you face continuing with your mark.