[Retric]

'Paid for my options before leaving the company.' means #1 is irrelevant.

Chances are there was some issue with preferred vs common stock.

[billmcneale]

No, it's not uncommon for startups to let you buy the stock before it even vests. The company will buy it back if you leave before you vest (although you usually don't even bother since they are worth pennies).

If the OP left after staying less than a year, they most likely didn't vest anything.

[fourk]

For reference, I had vested the shares that I purchased.