Time for coolant change?

2001, 4.0, AW4. I bought it 6/09 with 134,000 miles on it and did a coolant flush and refill with 50/50 Prestone. In 7/10 I changed the waterpump, radiator, thermostat and refilled what I drained out with 50/50 Prestone. Now at 177,000 miles the coolant is looking kinda rusty orange. It's still transparent, just not green anymore. Is this normal and it's time for another flush and fill or do I have something to be worried about?

A year of use on the last change? That's not bad and probably time for a change.

yup that seems decent