When I woke up, I checked to see how Apple’s stock did since the quarterly report was released. The report was excellent: Apple blew past expectations and hit record sales and profits (again).

Because the report came at the end of the trading day, most of the reaction came after the market closed. Already, Apple had gained $4 (or 2.3%) at market close–but after-hours trading has Apple up an additional $12, or about 7%, for a total gain for the day of $16, ending up at over $186 per share. For me, that equals roughly a whole month’s salary gained in a single day.

That also makes it official: Apple stock is now double what it was when I bought it less than a year ago.

I am beginning to get the feeling that this is the main reason Apple has decided not to split the stock, at least for now: the value is going up too quickly. If Apple were to split the stock, that might give it too much “exuberance.”

This is not to say that Apple’s stock is going to fall. Yes, I would expect it to drop from its present height in the next week, maybe by as much as $5 or $6, but then it will almost certainly rise again. Even with a market cap (all shares of stock x current stock value) of $162 billion, Apple still represents growth. It currently has only about 6-8% of the market in computers, is releasing a new version of Mac OS X later this week, has a strong hold over the digital player market that shows no sign of ebbing, has just started to break into the lucrative cell phone market, and could enter other markets in the future. And we’re just getting into the hottest quarter of the year. There is so much room for Apple to grow, it’s hard not to see it getting bigger.

But the tricky question is, when will it top out? Eventually, it must; but from the looks of it now, that won’t happen any time soon.