Well now, I think the point to remember here is "A quart or more per day". They're not saying you're going to drop dead after your first cup of juice. What happens, sadly, is that over time the grapefruit juice and statins compete for enzymes, stress the liver, and damage is done.
This happens, with a LOT of medications. Take most acid reducers, and you'll have issues with Iron. Take an MAOI, and you really CAN drop dead from a slice of old cheese.
The OP may be very alarmed, but he should be although the risk to his health based on his description is negligable. The difference between legal boiler-plate and medically established fact is not something for laypeople. It CAN be determined, if you know how to read a study and evaluate it for quality. That is in fact why GPs, AND the pharmacist should be giving verbal warnings.
Ah, and lots of medications have "drop dead" warnings for 2 reasons. The most common is that ANYTHING can cause an allergic (anaphylactic) reaction in a person. Take IV Iron infusions for instance. They're not uncommon for a variety of common causes of IDA (Iron Deficient Anemia), and when you get one there WILL be someone with a crash -cart waitng. Iron isn't dangerous, but some people go right into anaphylaxis, which is pretty close to "dropping dead" short of cardiac arrest.
On THAT fun note, there are the "hardcore" drugs that don't cause problems, but if you are unfortunate enough to have a long QT interval, or some other arrythmia, it's lights out. Most antipsychotics will drop someone with Long QT if you give it to them often enogh, and it's a Russian Roulette setup each time.
Bottom line: If there is an effect, there is the possibility of adverse reactions. That chance is usually poorly evaluated (as both too risky, and not risky enough) by most non-medical professionals, and plenty of MDs. If you're really concerned, double check your regimen with a pharmacologist... but to be frank, the combo of Simvastatin and Grapefruit would cause a LOT of other symptoms before "death".
Generalized pain would be a big giveaway, and the jaundice and slow liver failure would be another hint.
Finally, there are people who lack certain cytochromes and fail to produce enough of enzymes that are used in multiple metabolic processes. Those people, who might already be at their body's limit with a grapefruit, are overdoing it with the statin. There would be warning signs however as Proton Soup mentioned. There always are unless sudden death really = SUDDEN.
Killer Grapefruit... priceless... :zzz: