then it might be just a topographic survey, for civil design of drainage improvements, sewer, utility improvements, etc. Usually they will collect enough corner evidence to establish any public right-of-way but not necessarily enough to analyze for a full-blown property survey. If your neighbor has been maintaining things in the right-of-way, there is not much she can do: "The King will get his due". Utility easements might encumber a certain width of private property adjacent to and outside of that public right-of-way or side/back property line. The utility(s) in question has/have specific rights and restrictions spelled out in the easement documents or on the plat (if platted).
If you saw the surveyors digging up and measuring corner evidence or setting property corners in back yards/lines, it is probably a property boundary survey from which a Record of Survey and property description may likely be prepared and recorded with the county. Part of their job is to uncover, measure and record all available monument evidence, lines of occupation, etc. to analyze and prepare for subsequent filing with the county. In that case gaps, overlaps, encroachments and/or non-prescribed uses as you mentioned may be noted on the survey.
If your neighbor's property is an unplatted parcel and not part of an adjacent platted subdivision it might have some senior rights. That is where surveyors, attorneys, courts, lots of money and likely bad feelings come in to play. Suing for adverse possession or some kind of prescriptive right, IMO, is an ugly, expensive, somewhat rare, last resort thing to do. I've seen once friendly neighbors turn into bitter enemies fighting over little strips of land, that in the big picture don't amount to much. It's far better to try and iron things out before it gets to that point.
Long story short: Go to your county assessors office, ask some questions, see if there is a recently recorded survey you could look at, etc. Maybe ask the local highway district if they are planning on anything. Or if you know the name of the survey firm, they might be willing to shed some light. If they were city or county surveyors, my guess is they were doing a little design topo for some kind of improvement. Good luck and try to stay out of court.
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