Elionwy- The way a child's circumcision looks can be very different from an adults because their penis has not yet grown to adult size. A lot of times the penis seems pulled in or the skin seems bunched up because of the size of the penis, but they grow out of it in a few years and it will look more the way you'd expect.
If your son has adhesions (skin grown back to the glans so you can't see the whole edge of the corona) You might want to do some research at CIRP on what causes them and how to treat them (or not) This is a very common circumcision complication and it happens to boys circumcised at the hospital too, it's not something that would only happen because of the technique the mohel used- it is the nature of the body to try to heal and recover the internal organ that was exposed.
This is a picture of a boy with adhesions:http://www.circumcisionquotes.com/images/slide1.jpg
If adhesions don't resolve they can become full blown skin bridges:http://www.circumstitions.com/Restric/Botched1sb.html
they usually do resolve though:http://www.cirp.org/news/ponsky2/
Also some circumcisions look very loose, but as the child grows the appearance changes: http://www.rogerknapp.com/medical/circ_incomplete.htm
These pictures clearly demonstrate why the idea of recircumicsing to remove what someone else percieves is "extra" skin, could be a grave mistake.
I hope these pictures ease some of your concern. It is frustrating that clear depictions of these conditions are so hard to find, because there are a lot of people like you who just can't tell what they are seeing.
You might want to do as someone else suggested and speak to the mohel and/or your son's pediatrician. The Mohel might have some advice but also might want to give more detailed aftercare instructions in the future so parents are better equipped to avoid/cope with things that might happen.