Spark Web UI port

I log on to the console using labs.itversity.com/user/lab which is on gw02 and ran a spark job using spark shell. but when I go to the Spark Web UI using lab website, it takes me to gw03.itversity.com:18080/ instead of gw02 and I cannot find mine Spark job.
After 2 hours or so, I saw my job on gw03. Why did it take 2 hours plus to show on Spark UI?