My carpet is wet in a 18 inch diameter circle around my basement floor drain. The weather has not been rainy at all, not for at least a week. Does this mean I'm getting back up from inside my house? It does not have a sewer odor.

What would be the first trouble shooting someone would suggest or should I just call the plumber?

I think this has happened at least once before because some papers in that corner got wet. I never saw the back up, just found the water damaged papers later.

Sounds like you have a partial clog downstream from the floor drain. Did this happen after you ran a load of laundry? The solution would be to snake the house main. This can be done in your basement from a clean out in the stack if you have one, Otherwise you must snake from a roof vent. Good luck, Tom