No real need to be concerned. It seems that it is a standard disclaimer on many ADR's. Some people making a reservation for 1 or 2 have seen the same thing.
It is possible, but highly unlikely. I wouldn't worry about it.
I have been down there alot of times with a party of 7 and 9 and they have always kept us together. They have asked us before if we wanted to seperate to sit down right away, but we said no and that was no problem at all we just had to wait a few minutes extra which was no biggie. With a party of five you will have no problem at all