Possible warp gate bug

I managed to take the star about an hour after he left it, but when I built a warp gate there, his ETA suddenly went drastically down. Are warp gates supposed to affect ships after they have started a normal flight? Or is it a bug?

A screenshot with a ruler.

Carriers fly normal speed of 0.3333 LY per tick.
All carriers fly 1.0000 LY per tick between two WGs.

Two WGs are required at both departure star & destination star for the faster carrier speed. The carrier speed can change when the WG count changes between two or not two. All carriers are affected from any empire.

If you see an enemy carrier borrowing your WGs to attacking your star, then you can choose to destroy either one of your own two WGs to slow him down.

Ok, thanks. I just find it kinda weird for the speed to increase mid-flight.

Yeah it is odd, but so critical to the strategy of the game. Once you get used to it, you will like the way it works. The way I think about it is, each tic a carrier travels between warp gates is like it traveling 3 tics instead of 1. So when doing your calculations you can use that rule to figure out where things will be the next tic if you destroy/add a warp gate.