http://www.epdmcoatings.com/
I used this stuff when I patched an area of my roof that was rotted. I assume this is what you are talking about... a liquid EPDM that you can "paint" on and it bonds to existing EPDM and creates a seamless patch. Worked GREAT, but a little messy.
2015 Ram CTD
2015 Jayco 29QBS