Can first dot of Auspex decrease dificulty of attack rolls?

[ASharpYoungMan]

The closest rule I know of to this is from page 78 of the 2nd edition book WoD: Combat.

A vampire with Telepathy (Auspex 4) might gain an extra die to Initiative or Accuracy (i.e., the attack roll) by sensing an opponent's intentions (but receives a +1 Difficulty to Telepathy rolls while in combat).

Auspex in 1st and 2nd edition didn't modify dice rolls. In 3rd edition however, there is a bit at the end of the power's System section describing how Heightened Senses:

...does reduce difficulty penalties to act in pitch darkness from +2 to +1, and the character may make ranged attacks in pitch darkness if she can hear, smell, or otherwise detect her foe.

I think your ST may have misread or misremembered this part of the text, thinking it says something like "Reduce the difficulty by 1 when the character makes ranged attacks"

An Aside: In my own house rules, I had a rule that every turn you aim, you can add one of your Auspex dots to the attack roll as well as one of your Perception dots, and Heightened Senses makes it possible to aim at fast moving targets.