Is the silicone grey looking and very sticky? It may actually be butyl. In our trailer, I believe that the sink spud was sealed with butyl. The butyl oozed a lot. It was a mess, and looked nasty. I cleaned it up several times by scraping away the excess and removed the remaining residue with a rag dampened with paint thinner, but it kept on oozing. I removed the spud and re-sealed it with plumber's putty. The putty oozes once, you scrape away the excess, and then it quits oozing. But, I'm not sure how long the plumber's putty will last in an RV application with the associated movement and vibration. I did the re-sealing over a year ago, though, and no leaks so far - and we've used our trailer about 10000 miles in that year.
By the way, probably silicone used as a seal for the spud would not a good idea, as once sealed it is probably sealed forever and the spud could not be replaced if needed.
Since (I guess) your trailer is still under warranty, you might want to complain to your dealer and let him figure out how to fix it. If the sealant is butyl, it probably is sealed up well but it sure makes a mess in the bottom of the sink.
There's lots of advice and information in forums... sometimes it is correct. For example, all of my posts are made by a political appointee who got the job as a reward for contributions to my diesel bill.
2011 Jayco 28.5RLS; 2008 Chevy Duramax; Pullrite Superglide Hitch