If it's not a warranty thing, I would (and just did a few weeks ago) use Dicor lap sealer (in a tube similar to caulk but is "self leveling") forced under the retaining cap (or whatever it's called) then I covered the entire width with Eternabond tape. The story is that you (we) will NEVER have to redo that seam again !!! The Dicor product is recommended by the EPDM roof manufacturer and is avalable at the local RV supply store. I did the entire length, both forward and aft and the screw channel with one tube. Eternabond is evidently the RVers prayers-answered/dream-come-true. It can be purchased from here as cheap as anyplace
http://bestmaterials.com/detail.aspx?ID=11341 It's a great thing to have in your RV toolbox !!