Laura,
I'm guessing that the "sinemet speedball" you experienced was a result of dose overlap with your last evening levodopa.
Regarding possible caffeine involvement, I routinely drink my first AM cup of pretty strong coffee within 15 minutes of my first levo dose with no noticeable hyper effects.
Who knows?! We are all so different.
Robert

p.s. Did you end up knitting double speed?