What a stroke of luck...

I was fortunate to purchase a 2009 Prius (127,xxx mi) with minor cosmetic damage (Carfax says it occurred back in 2009) for $3,500. Taken it through carwash a few times already, and in the process of cleaning the cloth seats and de-odorizing the damp smell. I am now sure the seller undervalued this gem of a 'tank'... After taking it to the local Toyota dealer for an oil change (multi-point inspection returned with good marks) only the tire-pressure sensor system revealed one or more sensors could be out ($200 something to replace one sensor and then re-establish connection to the main-brain). I received an email from Toyota offering to buy my sweet find for $5,800. Imagine my surprise!!! I could make over $2,000 in over 3 days of owning my sweet 2009 Prius... Of course, I was not tempted and look forward to my new relationship with this Prius! (I've had a great run with Subarus and was intrigued with hybrids, and when the opportunity presented itself... I jumped!) LOL
I am aware that the hybrid battery pack will probably go out around 150,000 to 180,000 miles, and most likely will have to fork out another $2,500 for a replacement, that still leaves the total price for my Prius at under $6,000 in hopefully 2-3 years. Still a great deal...
This forum has been so helpful (thank you to all who asked questions and to all that offered answers and suggestions!), I am slowly reading through the owner's manual. ha!!!
Have not gotten to the point regarding why the hybrid battery bars turn to lime green from the normal blue from time to time, but am happy that the level does go up to 7 bars occasionally. (Should I be worried or happy?)
The only thing that concerns me right now is the blinking light indicating 'slipping' or sliding when I drive have driven about 15 miles on the interstate! It seems to suddenly come on around the same underpass and at first it alarmed me as I thought it was a warning sign. I'd slow down, look to see if I was weaving in my lane (no I wasn't) and don't really know why it came on? When I got home I looked it up in the owner's manual and pleasantly found out that it was not a warning that something was wrong... and that it normally comes on when the system is engaged. (sigh of relief!) I've driven over a million miles in my 5-6 trusty Subarus, so I don't think I'm that bad of a driver... and the road when this light comes on is not wet, moist or hazardous in any way I could tell, so what is going on??? Does this light just automatically come on after driving 15-20 miles on the interstate? (or is some benevolent spirit inside my new Prius warning me to be more careful of upcoming road hazards?) LOL
Lastly, can I turn off this system or is it permanently on for safety?
Again thank you! Blue skies...