No big deal…just wondering if anyone has had any pblms with the little soft rubber cover on the Tandem pump charging cord socket. I lost one end cap completely years ago while I was on the Medtronic pump. It never seemed to cause problems but I did wonder if I was letting “stuff” get inside the pump where it doesn’t belong. On my current pump, which I only started wearing in April, it seems not to fit real tight. So, like my wife would tell you, if I can think about it, I can worry about it! 
Mine fell off, after a month I couldn’t get it to charge and had to replace it. I don’t know if it was the cover or if the charging port was bad. There was a small crack in the charge port housing.
I drop sometimes and the case doesn’t protect that corner.
You can get a new flap just call and ask for one
As @Timothy said, you can call Tandem and they will send you a 2-pack for free. Or if you don’t want to deal with calling Tandem, you can get them on Amazon.
Tandem will send you free replacements as long as your pump is under warranty. Just call and ask.
I checked at Amazon: the item is “Currently unavailable.” Sigh.
I still have mine…but it no longer fits over the USB socket 
Or, at least, it doesn’t stay attached. But that’s no biggie, since I always wear my pump inside a (Medtronic!) belt case.