Engine light on & smoke/steam from tail pipe

Yesterday, I bought a used 2004 Grand AM SE1 with 35,627 miles on it. Drove it home with no problems visible at all. Thought I smelled slight odor of exhaust on highway but nothing that lasted nor smelled extreme. Today the "service engine soon" light went on right after I started the car. I revved it a bit and when I did, I noticed some white smoke or steam coming from the tail pipe. When I got out to inspect it there was a bit of water leaking from the tail pipe. Nothing leaking onto the ground from the engine area at all. There was an extremely faint smell of exhaust that dissipated quickly. The "smoke/steam" does not linger in the air like a haze, and is definitely a pure white. It's still under obligatory 90 day warranty and when I called the service center they told me to bring it in on Monday for servicing. Two questions: 1.) Is it safe to drive the 20+ miles to the service center via interstate highway, and; 2.) Is this indicative of the early signs of something major that's going on with the car? I've never purchased anything pre-owned and was wary to begin with. I hadn't noticed anything amiss when I inspected the car before purchase and it seems to drive just fine. Now I'm scared to death I bought a lemon that I'm stuck with because it's used. Bear in mind, I know absolutely zero about cars. I see an engine light on and I freak out. Thanks for the help.

It is normal for white smoke to come out an exhaust pipe and for water dripping from the tailpipe. There are any number of normal causes for the white smoke. One example is that condensation often forms inside an engine when it is shut off and when you restart it, the condensation burns off. Another normal cause occurs when it is quite cool or cold out. The temperature differential between the outside air and the hot gases exiting the tailpipe cause white steam, not dissimilar from a jet aircraft. In either of these circumstances, a bit of water also exits the tailpipe. Another common cause for excessive water coming out the tailpipe is from buying gas contaminated with water. If you think this may have happened, fill your tank up at a different station than where you normally go. And a tank of high test could be beneficial.

Don't you also have the balance of the manufacturer's warranty?

It is unclear from your post whether the "service engine soon" light stayed on or if it just came on and has subsequently gone off. If it went off after you revved it or if it went off the next time you restarted the engine, you really shouldn't have anything to worry about. If however it has stayed on since first coming on, I'd be leary of driving it 20+ miles.

I seriously doubt that the "service engine soon" light has anything to do with what seems like normal condensation coming out your exhaust. You really have little need to worry about this being an early sign of problems to come. The 2004 Grand Am and Grand Ams in general are very reliable and nice cars to drive. My son had over 150,000 miles on it before any serious issues. And then he had to replace an intake manifold gasket (common problem on the earlier Grand Ams) and his heater core. The cost wasn't too bad for either, but you needn't worry about the same problems.

Take your car back to the dealer as soon as you can and they will check the computer for the reason for the "service engine soon" light and will fix it. Don't be too concerned. It's most likely some minor problem like a loose hose or some such thing.