I know it isn't very popular here, since it goes against indexing and diversification, but if you know what you're doing in the stock market, having a high concentration in a few stocks isn't the worst thing.
I've had AAPL since 2004, and bought more during the dip when everyone felt they were dead in the water. Yet they still churned more and more cash flow. If you're not comfortable reading financial statements, 10-Ks, and doing fundamental analysis, then yes, you should probably get out and not hold individual stocks. Index funds are also very likely weighted heavily with AAPL as it is, with it being the largest company and all.
If you think that there is still room to grow, that the discounted rate of future cash flows exceeds what the market is currently valuing the company at by a HUGE margin, have a long-term timeline and do not get trigger happy, then yes, being in AAPL (or any other stock for that matter) is good. But if you aren't really sure what you're doing, and are merely investing because you think "the iPhone will sell well" without any understanding of how that will impact future financial performance, then sell now and index 100%.