Yeah I suppose it could be. I put some of the fuel in a jar to see if some water would separate out, but didn't see anything. I even ran the system for a minute first to make sure the tank was mixed up a bit.
The tank itself I think will be fine, I had the sender unit out less than a year ago and had a look inside with a torch, no debris or rust to be seen.
But I think the most sensible thing sounds like to just run the tank down again and put some fresh fuel in, I'll go to a different servo also.