Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of online postage provider Stamps.com (NASDAQ:STMP) surged 24% today after its quarterly results and guidance.

So what: The stock has slumped a bit in 2013 on concerns over slowing growth, but today's first-quarter results -- adjusted EPS spiked 38% on a 13.5% revenue increase -- and upbeat full-year guidance naturally eases some of those worries. In fact, Stamps.com hit its highest level of total paid customers -- and added its largest number of new paid customers -- during the quarter, giving investors plenty of good vibes about the company's prospects going forward.

Now what: Management now sees full-year adjusted EPS of $1.95-$2.15 on revenue of $125 million $135 million, nicely above its prior view of $1.75-$1.95, and $120 million-$130 million. "[I]n summary, our Core PC Postage business model of recurring revenue and high gross mergers is demonstrating continued growth and operating margin expansion," . "We are seeing record setting performances across many of our financial and key customer metrics." With the stock blasting through its 52-week high today, and trading at a still-lofty price-to-sales of 3.5, however, I'd wait for some of the excitement to fade before buying into that bull talk.

Interested in more info on Stamps.com? Add it to your watchlist.

Fool contributor Brian Pacampara has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.