While cleaning the roof of my 2012 Autotrail Tracker I found that all the silicone / adhesive used to glue the roof vents to the roof has gone really rough, see pictures. I suspect it hadn't been smoothed off at the factory. I scraped a little bit off and it was still sticky under the hard surface. As far as I know none of the vents are leaking going by my damp meter, so I'm inclined to leave well alone. Is this normal for an 11 year old motorhome?