It must be the paragraph composer.
Moving either or both the small words to the previous line does not leave enough room for the next word "solutions", so there would be a huge gap at the end of that line. That is exactly the kind of balancing act the paragraph composer does: it is better to have four lines with a score 0,-1,-1,0 than 0,-1,0,-3, where the last full line is much shorter.
(Numbers are for illustration of the idea only. The actual line weighting may differ by as little as a tenth of a million or smaller.)