Welcome to the wonderful world of flats!
They're like buses - you wait forever and then 3 come at once!
To add to the already excellent advice given - you don't specify whether the flat was on the same wheel or not.
The one thing to watch with flats is tyre pressure. Under-inflating the tyre will make you prone to more flats - especially pinch flats (often called "snakebites") - where the squidgy inner tube becomes nipped between the tyre and the rim. A friend of mine suffered from this on a ride, after having just mended a puncture minutes before! It's difficult with road tyres because of the high pressure needed - you often can't get so high on a small, transportable pump - but you should definitely check the pressure when you get home and get it up-to-speed with a track pump.
You're doing pretty well to go 1,500 without a flat!
As Melody says, always run your finger along the inside of the tyre when fixing a flat - even if you think you've got out the pesky glass or thorn that caused it - it's amazing how little shards can stay invisibly embedded and will give you another p*ncture once you get going again! The touch test is much more telling than eyeballing a tyre.