Readjust the rears.....
While turning the drum... . adjust the self adjuster until the drum won't turn by hand at all. Back off a little bit until you feel comfortable..... This is what I do... .
Sorry it sounds so vague, but this is how I do it... . and it has seemed to work good so far.
It's also possible that you have some crud on the drum or the shoes... . that will cause it to hang up and be really 'grabby'. This is common in the mornings when moisture builds up overnight... . once the dew is gone... the drag usually disappears too.
Hope this helps,
Matt