Yes, you can try to clean it off the dome like Tom E advises. He is very talented and knows a lot more than me. Alcohol and a cotton-tipped (Q-tip). You can actually scrub the dome. Just don't put so much pressure you tear it off.
Tom E may have a point about dedoming the T5 and it getting too warm tint as a result. Most lights with T5's in my experience are on the cool side of neutral though. If you dedome, the gasoline method is generally thought of as the best way. Tom E may have been the person that thought of it first. Here is a real good thread on the topic.