I tried to explain it above but maybe I just can't explain it. Maybe you'd just have to be in my (our) position to understand. And the fact that my co-host also felt that way sort of validates it.
If you take out the factor of the venue for a minute, and imagine that we were giving the party in one of our homes, can you imagine the guest of honor sending a forward scout like that? It would be rather awkward. Well, in this case, although the venue really was her stomping ground, it was still, at least for the evening, our place. We had spent a lot of time, money and effort putting the party together over the last few months, and then spent two hours carting stuff in from our cars, getting tables set up, coordinating everything the three of us had put together in order to make it look nice in what started out as a big empty room with some tables & chairs. By the time EarlyGuest arrived, we were in the final moments, doing the last minute stuff.
So, in other words, at the culmination of hours of planning and doing, the idea that we'd need someone to swoop in and sort of make it all happen for us, was a bit off-putting. I'm sure you're right that they were both just trying to be helpful, but from our point of view, it didn't quite come off that way.
Again, I'm going to emphasize that neither of us would say anything at all to the GOH or to anyone else, that we both just discussed it between ourselves and then brushed it off, that I'm only posting it here as an update and that it is now a non-issue.