Has my gelding been castrated properly? :S

[Equestria]

I've noticed this quite a while back, but haven't really thought anything of it.
He does show slight stud-like behaviour in the field at spring time especially, and has been seen 'mounting' some of the mares and even a gelding! He is only 5, and apparently he got castrated early. (He was born in the wild.)
However, on his passport there is no castration certificate, or signature, so I'm confused.
Anyway, he has a little lump sort of thing on the left, it's not hard at all, and it's quite narrow. (It doesn't look narrow in the pictures, but it is, trust me. xD)
What can it be? Here's some pictures:

Ignore the little sarcoids, I was going to get them removed, but it just costed too much money for the cream, and they aren't hurting him in any sort of way. ^.^

 

[[59851]]

can't see the pics

 

[Equestria]

Really? My computer lets me see them. :S
I'll try the links:

Picture 1
Picture 2
Picture 3

 

[AFlapjack]

Really? My computer lets me see them. :S
I'll try the links:

Picture 1
Picture 2
Picture 3

Nope still not working.

 

[Equestria]

Hmm, that's strange... Or maybe not. I uploaded them from my phone the lazy way; I sent them to my email. Perhaps you can't view the codes from email attachments?
Anyway, I just got my phone lead out and put them on Tinypic, so hopefully you can see them now!

*Edit: I didn't realise they'd be so big! Sorry, hopefully you can see it still!

 

[*hic*]

Bloomin' 'eck "Tinypic" is a bit of a misnomer!

It looks to me as though what you are seeing is a just a fold of skin UNLESS there is something solid in there. The best person to ask would be your vet.

 

[Equestria]

Thanks, I did have a little feel of it, it's not hard at all, so hopefully it's nothing to worry about!
(By the way, I can't stop staring at the GIF in your siggy. xD)