Maybe Chinny was just going the scientific route and seeing if the iron was hot every time he touched it.

Realistically, Chinny would need a visit to the doctor if his memory was really that bad.

There are a lot of factors with memory.  There are also some medications that affect memory.  A lot of diseases affect it too, as well as depression and anxiety.  Exercise is really considered to be something that can help memory, but it does seem like lack of exercise is detrimental to memory too.