I'm not familiar with that brand. But most heaters are just a tube and my guess is the rubber (?) bit on the end is just stuck on for protection of the glass. I wouldn't worry about it but...
I do recommend that you have a thermometer in the tank and check it daily (I do this anyway). I also recommend that you have a spare (tested) heater for just in case. Heaters typically stop working in 1 of 2 ways
- They don't heat up. Probably not a massive deal if you spot it early as you can get another one before the tank has cooled too much
- They don't turn themselves off when they get to the correct temp. This is a really big deal if you don't notice because it will turn your tank into fish soup.
I have digital thermometers independent of the heaters mounted where I can see them when I am anywhere near the tank. So it really is no effort to check everytime I'm in the room.