The T-Rex head started having problems many years after that ( borderline funny ) incident with hot hydraulic fluid bring squirted on people.* Although I can't quote you the exact years, I recall the leak issue being in the first year and seeing that T-Rex head working fine for about a decade after that. Only in recent trips there I've taken in the last 4-5 years have I heard myself, members of my party and other park-goers constantly commenting about "Didn't that T-Rex used to be recessed farther back in the dark before it came out?" To hear that many people all asking the same question makes me think that it's not a mis-perception. There's got to be something to it. I think a lot of us remember that thing being further back up in the dark then coming out at you.
* As I recall, in the opening days of the ride people were passing the Dilophosaurs ( aka - Spitters ) who would shake their neck frills and spit water on them. Customers would expect it to be poison like in the movie but of course it was just water. ....except for that one day that they got scalding hot hydraulic fluid instead, and then yeah... That was probably a pretty miserable time to be on the ride, trapped on a boat until you could get to medical attention.