Little smoke out of tail pipe

[Shawn_hollen]

I looked on all the threads and didn't see any pertaining to this. It is prob not a big deal but I've had a lot of small things go wrong and had to fix and or replace. So in the last 3 months I have put in a thermostat plugs, coils, secondary throttle position sensor, changed oil, A/C Compressor, changed all fluids, both back speed sensors, both knock sensors, battery, battery terminals, need to replace radiator it leaks a little, will be changing throttle body tomorrow, and accelerater cables, my check engine light came on last week and it was my EGR valve so I cleaned it and reset the light it stayed off till today it came back on when I left the store on my way home I drive to the store and a couple other places drove it about 20 min or so. Was at the store for a couple hours with the family. I drove home and stopped and got food so drove it about another 20 min. When I got home I went in reverse to finish parking I looked in review as I was backing up and seen smoke wasn't thick or a lot. Couldn't see the color of it cause it was dark. It has been running great for the last 3 weeks. I revved up a couple times still revved good idled good. So my question is where should I start looking for the reason for smoke. In the morning when sun comes up I'm going to see if it smokes again to see the color. This is the first time I've seen any smoke in the 2 years in had the car. I have a 99 q45 with 185k miles thanks.