Macbook air wouldn't turn on until after I reset the SMC. Does this indicate any further problems?
Resetting the SMC usually solves power-related problems (fan handling, sleep mode, etc).

The procedure is quite simple and documented, meaning that such problems are quite common and usually do not indicate the existence of anything worth worrying about.

Actually, it is advisable to reset the SMC and PRAM (start up with Command, Option, P, R pressed) periodically; also, while you're at it, you might want to repair disk permissions (using Disk Utility in the Utilities folder) and verify the Hard Disk as well.

If you keep your Mac well maintained, it will remain healthy for a long time: my MacBook Pro is 4 1/2 years old and still rocking thanks to an SSD upgrade ;)