Hi Lauren - Absolutely you should be concerned. This is a job for a real estate attorney...those guys should wear spandex with an S on their chest! You can do some background digging in the public record yourself to find out who the legal owner of record is, and if there are liens on the property. You might even be able to find copies of old deeds. Check the county clerk's office about the liens. This is tedious work, but can be enlightening. The county property appraiser's office will be able to tell you the owner of record, and the whole history of sales on the property. But at the end of the day, you'll still want a real estate attorney (read: Guru) to help you sort this one out.
The reasons why you should be concerned are unending! You could be buying a home the seller has no right to sell! You could be buying a home with liens on it that you'd be responsible for paying before you could get the deed yourself. You couldn't close without clear title if you financed - title insurance would not be issued, and the bank wouldn't let you. And remember the old adage, "If it sounds too good to be true, it usually is..." Protect yourself and, well, cover your assets. Get an attorney - or RUN, Forrest, RUN!