I often wonder why people randomly capitalize words, or use improper punctuation.
Happens to me a great deal. I tend to capitalize nouns when I don't concentrate. In German, all nouns start with a capital letter (nouns are considered as and treated like names). I guess it's only natural that one slips back into one's own language when one gets tired, as it's the language one is most fluent in (though I do dream in English, occasionally)