Such usually doesn't surprise me much. You can only get one vote per node per voter, so +45 vs. +3 means 45 people got at least a little something out of the first node, not that even a single person found the first node better than the second.

The shorter, faster, and simpler a node, the greater the number of potential voters who can appreciate it (slow nodes are seen by fewer, long nodes are often skimmed or skipped, complex nodes are often not fully understood). Perhaps even more significant is that long/complex nodes just take long enough to process that the impulse to vote gets lost (and are more likely to give the reader some minor point they don't like and so give them reservations about upvoting it).

Or perhaps I just see patterns that make sense to me even when there are none. (:

Luckily, intentionally attempting to take advantage of this quirk usually "rings false" and doesn't work very well for very long, while most authors tire of such XP whoring anyway, so the consequences aren't horrid.