This immediate score you see has nothing to do with the way your Lehman rating is calculated. It does not show any of the adjustments for partner or opponents, does not say anything about the smolians you will earn for the board, nor is it the final IMP or matchpoint score you will receive on the board. Sure, you may have outscored your opponents at the table. But the sponsors put a nice stack of smolians on the probability that you would not only beat those opponents, but beat them even more severely than you did. If you didn't beat the point spread they had on you, they lost money and you disappointed them.
Some people are pleased by doing better than others in some measurable way, and that's fine.
You may interpret the measurement scales in any way that is useful to you. Subtract your rating from 100. Now play for a while at such a table. That is, the sponsors assume your partnership will beat theirs by that point spread. For further details about the principles and calculations of the system, see the fuller explanation .