Apple's stock has doubled in the last year. Here's why a longtime investor says it's not time to sell. (AAPL)

· Apple's stock has essentially doubled in the last year, giving it a price-to-earnings valuation at the high-end of its recent range.
· But that doesn't mean it's overpriced, said Dan Morgan, a senior portfolio manager with Synovus Trust.
· Apple's stock sold off in late 2018 and early 2019 after its sales plunged in China...