antifreeze in the exhaust pipe 02 yz 125?

I am rebuilding the top end on my 2002 Yamaha Yz 125 and when I took off the exhaust pipe about half a cup of antifreeze poured out of the pipe how did this happen is this normal all the clyinder gaskets were fine?
Also when I move the power valves one moves and the other one does not are the springs worn out?

I think it must be the o ring gasket it was melted and alittle thinner then the new one. The oil was clean when I replace the oil I also had the bike in a shed in -15c then moved to a warm garage where it will stay for good.
I have alot of hours on the bike 35 hours most of it trail riding I think I left it a little too long but the clylinder looks good and the piston is not too bad but it is time for a new piston and rings.
I tryed to remove the power valve but they are stuck in there I don't know how to get it out the valve move when I push on it with my finger it is just the casing is stuck in there any tricks on getting that out.