popping, squiterimg & strange noises.

[WooTeck]

I was running my rum 2 days ago I was coming through heads when i was interrupted and had to shut er down. I brought the keg in to my room as it was a cold night and I knew that I wouldn't be able to run again until today. I covered the top not realising that the pressure would build again any way when I realised I fixed the issue.

Today I was fireing up again and there was this pop made me jump as its never done that before.since then the still hasn't sounded the same. Louder than usual and with the a squitter every now and then.

Anyone got any idea what may be causeing it?
Eck

*edit its sounding normalish now just a lot louder. I'll wait until it heats up and go over it with a mirror.