Late Tuesday Las Vegas-based Allegiant Air pre-announced that it will report earnings for the first quarter of between $1.34 to $1.38 per share.

This estimate is far above the then-forecast estimate by analysts for the airline — which had estimated the airline would post a profit of $1.20 a share.

The airline will report earnings this coming Monday.

So why the uptick from previous company guidance?

Analyst Dave Fintzen with Barclays, who recently initiated coverage of the airline’s stock (we talked about his recent research note on the airline in the latest edition of PlaneBusiness Banter) said today that because the airline gave no details other than the higher EPS estimate, it’s a bit hard to know where the better performance for the airline was. Although he assumes it was all on the revenue side, with revenue probably outperforming even the previous management guidance.

So what is Dave going to be looking for when the airline reports on Monday? Any feedback on the airline’s booking trends in its new markets, especially Los Angeles, in addition to any updated information on where the airline is going to grow now — as we move into the second quarter and third quarters.