I am not positive I fully understand the question, but keeping one of those el cheapo foam rubber rubber brushes handy does this for me. These will absorb that little bead of paint just fine.
In fact, for cutting in the front of the house (I just finished all but the 2nd top coat of trim and the doors) I used a foam brush for cutting in exclusively. It worked better than I thought it would so I didnt bother with the bristle brushes I got. It was tedious at times but the sharp edge of a new foam brush allowed me to get some very sharp straight lines in areas where there was to be a color change (wood around window frames).
Another little hint that I taught myself was instead of using the small factory pre-cut paint rollers, I cut my own from larger rollers using a steady hand on the sawzall. I made a really fine edge which unlike the pre-cuts was NOT tapered on the end. I then pulled out any loose fuzz from the cut area. This small square edged roller allowed me to roll the area of the cut in VERY closely (~1/8 inch) which I could not have done with a factory made roller which is tapered on the ends.
Hope this helps.
I am sure real painters have a far more elegant solution to give ya. I'll learn from them too!