I would do some routine maintenance as described above, especially if you havent done it before or are unsure how long ago it was done. Anytime I break into a vehicle I havent worked on before I always start with the basics and get them outta the way. Staying on top of that will help prevent alot of issues from popping up later on. In addition to the above, go ahead and clean the MAF with CRC's MAF cleaner, change fuel filter, etc. Most problems that come up on this board are easily fixed with routine maintenance that has been failed to be performed.
If it gets worse let us know, but for the most part our engines are known for cooling system issues such as heads cracking and intake gaskets leaking. My advice is if its still running fine, keep running her and make sure to keep the fluids topped off. My exploder has 220K miles on it and suffers from some coolant loss. It runs absolutely fine, and quite well for its age and mileage, but losses a bit of coolant from time to time. Been driving like that for 50k+ miles. Until I start seeing other indicators or it starts running bad, I wont waste my time tearing into it...I have too many other projects to deal with anyways.