Very odd. What coach to you have? Year model? Is it under warrantee?
Im not sure I would can help you but perhaps you can temp fix with either eternalbond tape or dicor to prevent leaks?
Do you have another picture that shows more of the roof/end cap seam?
Is it leaking?
I guess to fix it right someone would remove bulge and then fiberglass smooth? Might be a lot of work for something that you cant see?
Hopefully some others can chime in and help.
2017 Axis / 25.4: Big Foot Levelers, Aims 1200 Watt inverter, Ceramic Window Tint, Full River AGM 6V batteries, Front Hellwig Sway bar / Rear Track Arm, Safe T Plus Steering Stabilizer, PD 4655 converter, Hard Wired Surge Guard, WEboost + WiFi Ranger, LED Headlights/Driving lights, TPMS, Surge tank, Tornado flush, Viair Compressor