When a single line such as:
. this is a test line tra la la la la foo bar bazz length1 length2 length3 length4 length5
is reformated (ctrl+k j) the leading punctuation is duplicated on the subsequently created lines. I can't tell if this is a feature or not - it seems like it might be useful in certain cases, however it interferes with long sequences of C format strings such as "%s, %s, %s, %s, %s" - the %'s are duplicated and sometimes moved around, invalidating the format.